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Benchmark DAC2 HGC and DAC2 L Instruction Manual

Reference Stereo Preamplifier PCM and DSD D/A Converter

Asynchronous USB

(Version 2.2 Firmware) (Units Manufactured or Upgraded after 06/10/2016)

Instruction Manual for DAC2 HGC and DAC2 L with 2.2 Firmware

Safety Information

Fuses

CAUTION: FOR CONTINUED FIRE HAZARD PROTECTION ALWAYS REPLACE THE FUSES WITH THE CORRECT SIZE AND TYPE (0.5A 250 V SLO-BLO® 5 X 20 MM – LITTELFUSE® HXP218.500 OR EQUIVALENT). THE FUSE DRAWER INCLUDES TWO FUSES. ALWAYS REPLACE BOTH FUSES AT THE SAME TIME.

AC Input Voltage Range

NOTE: THE DAC2 IS EQUIPPED WITH A UNIVERSAL POWER SUPPLY. THERE IS NO VOLTAGE SELECTION SWITCH. AC VOLTAGE RANGE IS 88-264 VAC, 50-60 HZ. THE PRODUCT MAY ALSO BE OPERATED FROM DC POWER OVER A VOLTAGE RANGE OF 125-373 VDC.

Power Cord

CAUTION: ALWAYS USE A GROUNDED POWER CORD. THE PRODUCT IS EQUIPPED WITH A STANDARD IEC POWER ENTRY MODULE. USE AN IEC POWER CORD THAT IS EQUIPPED WITH THE APPROPRIATE CONNECTOR FOR YOUR LOCATION. CORDS ARE AVAILABLE FROM YOUR DEALER.

Modifications

CAUTION: DO NOT SUBSTITUTE PARTS OR MAKE ANY MODIFICATIONS WITHOUT THE WRITTEN APPROVAL OF BENCHMARK MEDIA SYSTEMS, INC. MODIFICATION MAY CREATE SAFETY HAZARDS AND VOID THE WARRANTY.

CAUTION: CHANGES OR MODIFICATIONS NOT EXPRESSLY APPROVED BY BENCHMARK MEDIA SYSTEMS COULD VOID THE USER'S AUTHORITY TO OPERATE THE EQUIPMENT UNDER FCC REGULATIONS.

Repairs

CAUTION: DO NOT SERVICE OR REPAIR THIS PRODUCT UNLESS PROPERLY QUALIFIED. ONLY A QUALIFIED TECHNICIAN SHOULD PERFORM REPAIRS.


Contents

Safety Information 2 Fuses 2 AC Input Voltage Range 2 Power Cord 2 Modifications 2 Repairs 2

Features 4

Introduction 5 Applications 5 DAC1 Heritage 5 System Overview 5 Expanded I/O 7

Front Panel 8

Rear Panel 8

Quick Start Guide 9 Audio Inputs 9 Remote Control 9 Front Panel Controls 10 Front Panel Displays 11 Headphone Jacks 13

Operational Details 14 DIM and MUTE Functions 14 Bi-directional 12V Trigger 15 HT Mode 16 USB MODE Selection 17 Driving Power Amplifiers 18 HPA2™ Headphone Amplifier 18 Digital Pass-Through 19 Firmware Version Identification 19

Rear Panel 19 Inputs 20 Outputs 23 AC Power-Entry and Fuse Module 24

Internal Settings 25 Jumper-Configured Options 25 Removing Top Cover 25 XLR Output Pads 25 Headphone Switch Configuration 26 Headphone Amplifier Gain 27 Digital PASS-THROUGH Function 28

Rack Mounting 29 Benchmark Rack Mount Tray 29 Benchmark ½-Wide Blank Plate 29

Benchmark Technologies 30 DAC1 and DAC2 Family History 30 Hybrid Gain Control™ 31 Native DSD Conversion 31 Jitter-Immune UltraLock2™ 31 High Headroom DSP 31 32-bit SABRE Conversion System 32 Diagnostic Displays 32 Bi-Directional 12 Volt Trigger 32 Distributed Power Regulation 32 HPA2™ Headphone Amplifier 32 Differential Amplifiers 33 UltraLock2™ Clock System 33 Multi-Mode Asynchronous USB Audio 36

USB Driver Installation 37

Performance Graphs 41

Specifications 57 Audio Performance 57 Group Delay (Latency) 58 Digital Audio Inputs 58 Jitter Tolerance 58 Balanced Analog Outputs 59 Unbalanced Analog Outputs 59 HPA2TM Headphone Outputs 59 Unbalanced Analog Inputs 60 Status Display 60 AC Power Requirements 60 Dimensions 60 Weight 60

Regulatory Compliance 61 FCC and RoHS Compliance Statements 61 FCC Notice (U.S. Only) 61 RoHS Compliant Information 61 CE Certificates of Conformity 62

Warranty Information 63 Benchmark 1-Year Warranty 63 Benchmark Extended Warranty Options 64 Notes on Warranty Repairs 64


Features

HGC™ (Hybrid Gain Control) – combines a motor-driven active analog potentiometer, 32-bit digital attenuation, and passive analog attenuators, to achieve state-of-the-art performance

Low-Impedance Passive Output Pads – 0, 10, and 20 dB – optimize output level to power amplifiers and other downstream devices to maximize system SNR

SABRE - 32-bit PCM D/A conversion system, four 32-bit D/A converters per channel

SABRE – Native DSD D/A conversion system, four 1-bit DSD D/A converters per channel

Benchmark UltraLock2™ Jitter Attenuation System – eliminates jitter-induced distortion

High Headroom DSP - provides 3.5 dB of analog and digital headroom above 0 dBFS to completely eliminate the clipping of inter-sample peaks

Multi-Mode Asynchronous USB Audio 2.0 – 24 bit/192 kHz, DSD (DoP 1.1)

Driverless Asynchronous USB Audio 1.1 – 24-bit/96 kHz

Sample Rate Display – displays the measured sample rate, and format (PCM or DSD)

Word Length Display – displays the measured word length

HPA2™ reference-grade "0-Ohm" headphone power amplifier with dual high-current outputs (DAC2 HGC only)

HPA2™ gain jumpers for customizing headphone output gain for headphone sensitivities (DAC2 HGC only)

2 Headphone Output Jacks – one output has option to automatically mute main outputs (DAC2 HGC only)

2 Coaxial Digital Inputs – 24-bit/192 kHz PCM, DSD (DoP 1.1)

2 Optical Digital Inputs – 24-bit/96 kHz PCM

1 Coaxial Digital Output – digital pass through from USB, Coax, and optical inputs when jumpered

2 Stereo Analog Inputs – 2 pairs unbalanced (RCA)

3 Stereo Analog Outputs – 1 pair balanced (XLR), plus 2 pairs unbalanced (RCA)

IR Remote with metal housing provides control of all functions

HT Bypass – places analog inputs in a unity-gain pass-through mode, sets digital inputs to a calibrated output level - all inputs can be individually programmed

Polarity Switch – inverts the polarity of selected digital inputs

Mute – accessible from remote or front panel

Dim – Reduces output level by 20 dB, accessible from remote or front panel

Automatic De-Emphasis – automatically responds to consumer pre-emphasis bit (44.1, 48 kHz)

12V Trigger I/O – bi-directional 12V trigger can act as input, output, or both

Power Switch – very low standby power , <0.5 W at 120 VAC

High-Efficiency Low-Noise Power Supplies – only 12-15 W, 88-264 VAC, 50-60 Hz

Meets FCC Class B and CE emissions requirements

Tested for immunity to radiated and conducted RF interference


Introduction

Applications

The DAC2 is a professional reference-grade audio digital to analog converter with Benchmark's HPA2™ headphone amplifier. It supports 24-bit D/A conversion of PCM at sample rates up to 192 kHz. It also supports direct conversion of 1-bit DSD at a 2.8224 MHz sample rate. It is designed to be very transparent and this makes it well-suited for critical monitoring in studio control rooms and mastering rooms.

The DAC2 is also well-suited for high-end hi-fi environments. It includes a generous collection of inputs and outputs and can serve as the central component in any stereo hi-fi system. It provides D/A conversion, source selection, volume control, and headphone amplification. A remote control, 12V trigger, and home theater bypass function provide the features needed in a home environment.

The DAC2 is designed to directly drive a wide variety of power amplifiers and powered monitors. The balanced outputs include low-impedance passive pads that can be adjusted to optimize the interface between the DAC2 and the power amplifier. This optimization can provide substantial improvements in the system-level SNR and THD+N performance.

DAC1 Heritage

The DAC2 builds upon Benchmark’s highly successful DAC1 product family. The DAC2 maintains the familiar DAC1 form factor, but adds more features, and more I/O while delivering higher performance. Every DAC1 subsystem has been redesigned, upgraded, or replaced in order to achieve the highest possible transparency.

System Overview

The DAC2 adds these features that are not found on the DAC1:

• Asynchronous 192kHz USB Audio 2.0 • 32-bit D/A conversion system • Word Length Display

• Sample Rate Display • Polarity Control • Direct DSD D/A Conversion • -20 dB DIM • Bi-Directional 12V Trigger • Power Switch • Home Theater Bypass • Digital Pass-Through • High-Headroom DSP • Dual-Domain Hybrid Gain Control • Additional I/O

Lower Noise than the DAC1

The conversion system in the DAC2 is about 10 dB quieter than the system in the very quiet DAC1. To achieve this improvement, we selected the Sabre ES9018 8-channel 32-bit converter and externally summed two groups of four channels using two low-noise analog summing amplifiers of our own design. This 4:1 summing reduces the noise of the ES9018 by about 6 dB. The net result is 13.5 dB quieter than the converter in the DAC1. We have chosen to use 3.5 dB of this improvement to provide headroom above 0 dBFS so that intersample overs will never clip or overload the conversion system or the digital processing. This reduces the net improvement to 10 dB. Low-level musical details are faithfully reproduced over a breathtakingly quiet noise floor, and intersample peaks are faithfully reproduced without clipping.

No Clipping of Intersample Peaks

The DAC2 is one of very few D/A converters that can accurately reproduce intersample peaks without clipping. Intersample overs commonly occur many times per second in 44.1 kHz and 48 kHz recordings. Additional overs are added whenever lossy compression systems (such as MP3) are applied. Most converters (including the DAC1) produce bursts of distortion at every occurrence. In contrast, the DAC2 cleanly reproduces all intersample peaks.


Lower THD than the DAC1

Benchmark’s DAC1 converters are known for their very low distortion (THD and IMD). The DAC2 sets new benchmarks for clean and transparent musical reproduction.

Low Power Consumption

The DAC2 uses high-efficiency low-noise power supplies. Each critical subsystem also has at least one dedicated low-noise regulator. The unit runs cool while providing substantial power to the power-hungry low-noise circuits, headphone amplifier, and output line drivers. A power switch is included. The unit draws less than 0.5 W when off.

Low Magnetic Emissions

The magnetic components in the DAC2 power supplies operate at over 800 kHz. This allows the use of very small magnetic components that emit correspondingly small magnetic fields. This virtually eliminates all traces of line-frequency components in the output spectrum of the DAC2. This also means that the DAC2 can be placed in close proximity to any audio component without causing interference with the other component.

UltraLock2™ Clock System

UltraLock2™ provides the outstanding jitter attenuation of Benchmark's UltraLock™ system while providing a higher SNR.

Dual-Mode USB Input

The DAC2 has a USB input that can be operated in two modes; driverless USB Audio 1.1, and a high sample rate USB Audio 2.0. Both use asynchronous clocking to eliminate the USB interface as a source of clock jitter.

Asynchronous USB Audio 2.0

The USB Audio 2.0 interface supports DSD and 192 kHz, 24-bit PCM. No drivers are required for Apple operating systems. Drivers are provided for Windows operating systems at: http://benchmarkmedia.com/dac/dac2-drivers

Native Asynchronous USB 1.1

The DAC2 has a driverless USB Audio 1.1 mode that supports 96 kHz, 24-bit PCM with all operating systems. This mode provides a quick and easy connection to a wide variety of computers and tablets without installing a driver.

New HGC™ Hybrid Gain Control

HGC™ is Benchmark’s unique hybrid gain control that combines analog and digital gain control into a single volume control knob. HGC™ puts an end to the debate about analog versus digital gain controls, and passive versus active analog attenuation. The HGC™ system uses an active analog gain control for analog inputs and a 32-bit dithered volume control for digital inputs. Both types of inputs leverage the low-impedance passive analog attenuation system at the XLR outputs.

The dual-domain HGC™ system combines the high dynamic range of Benchmark’s HDR™ analog control (used in the DAC1 HDR) with the low distortion, and accuracy of digital control. HGC™ outperforms traditional analog or digital volume controls, including the two-stage DAC1 HDR™ system. Musical details are preserved over a very wide range of output levels. Analog inputs are controlled in the analog domain. Digital inputs are controlled in both domains.

The volume control is a servo-driven analog potentiometer. This control rotates in response to commands from the remote control while providing the convenience of manual adjustments with a physical knob.

http://benchmarkmedia.com/dac/dac2-drivers

http://benchmarkmedia.com/dac/dac2-drivers


Low-Impedance Passive Attenuators

Like the DAC1, the DAC2 includes low-impedance passive attenuators on the XLR outputs. These attenuators can be adjusted to optimize the interface with the power amplifier or powered monitors. This optimization places the volume control in its best operating range. This exclusive Benchmark feature can provide substantial improvements in the performance of the playback signal chain.

Native DSD Conversion

The DAC2 supports native DSD conversion. This feature was not available on the DAC1. DSD signals can be delivered to the USB or Coaxial inputs in DoP 1.1 format. The DSD signal is then routed directly to a bank of 1-bit DSD D/A converters. Four balanced 1-bit converters are summed together for each balanced output.

Digital Pass-Through

The second coaxial input (D4) can be reconfigured as a digital output. When operating as an output, any selected digital input is passed through to D4 without any processing. Optical, coaxial, and USB inputs can be passed through to the D4 connector. This even includes special signals such as DoP, DTS, Dolby Digital, even when these signals cannot be decoded by the DAC2.

Polarity Control

Each digital input can be inverted to correct polarity problems. Some listeners report that polarity is incorrect on some recordings, and that they enjoy an improved listening experience when this is corrected. To toggle, use the POLARITY button on the front panel or press and hold the ON button on the remote.

HT Mode

The HT mode sets the volume control to a calibrated level that is near its maximum setting. In HT mode the analog gain is set to 0 dB (unity gain). Likewise the digital attenuation is set to 0 dB (maximum output). The HT light is illuminated when the HT mode is active.

The HT mode is similar to the CALIBRATED switch setting on the DAC1 except that it is programmable per input. This flexibility allows seamless integration into home theater systems where the DAC2 handles the main left and right channels.

Bi-directional 12V Trigger

The 12 Volt trigger can be connected to other audio components so that an entire audio system can turn on and off in a sequenced fashion. The DAC2 trigger I/O could be connected to a preamplifier, power amplifier, or both. The DAC2 will pull the trigger I/O to 12 volts DC while the DAC2 is on. If the DAC2 is off and an external device pulls the trigger I/O to 12 volts, the DAC2 will turn on.

Expanded I/O

The DAC2 HGC and DAC2 L have:

• 2 stereo unbalanced analog inputs • 2 optical inputs • 1 coaxial input • 1 coaxial input or output

(programmable) • 1 USB input • 2 stereo unbalanced outputs • 1 balanced stereo output • 1 bi-directional 12 volt trigger


Front Panel

DAC2 HGC

DAC2 L

Rear Panel

DAC2 HGC and DAC2 L


Quick Start Guide

Audio Inputs

The DAC2 features two stereo RCA analog inputs and five stereo digital inputs (2 coaxial, 2 optical, and 1 USB). The coaxial and optical inputs accept professional (AES) and consumer (S/PDIF) data formats at word lengths up to 24-bits.

Tip: We recommend using the coaxial or USB inputs for sample rates above 96 kHz. Optical interfaces are not always reliable at sample rates above 96 kHz.

Remote Control

The remote control is designed to have a long operating range. In most applications it is not necessary to point the remote directly at the DAC2.

The chart at the right summarizes the functions of the IR remote control.

OFF Turns the unit off. Any devices slaved to the 12V TRIGGER will also turn off in a controlled sequence.

Press and hold the OFF button for 3 seconds to force the 12V TRIGGER off (only necessary when another device is acting as a TRIGGER BUS MASTER).

ON Turns the unit on. Any devices slaved to the 12V TRIGGER will also turn on in a controlled sequence.

Press and hold the ON button for 3 seconds to toggle the POLARITY function.

VOLUME Turns the volume up or down.

DIM Toggles the -20 dB DIM function.

MUTE Toggles the MUTE function.

Press and hold the MUTE button for 3 seconds to toggle the HT mode on the selected input.

INPUT Selects the inputs.

D1 Selects optical digital input D1.

D2 Selects optical digital input D2.

D3 Selects coaxial digital input D3.

D4 Selects coaxial digital input D4.

USB Selects USB input.

Press and hold the USB button for 3 seconds to toggle between the USB 1.1 and USB 2.0 modes.

Analog Selects analog input A1 and then toggles between A1 and A2.


Front Panel Controls

The front panel controls duplicate all of the functions that are available from the remote control.

The chart at the right summarizes the functions of the front-panel controls.

POWER Turns the unit on or off. Any devices slaved to the 12V TRIGGER will also turn on or off in a controlled sequence.

Press and hold the POWER button for 3 seconds to force the 12V TRIGGER off (only necessary when another device is acting as a TRIGGER BUS MASTER).

DIM/MUTE Press once to toggle the -20 dB DIM function.

Double tap to set the MUTE function.

INPUT Selects the inputs.

Press and hold both input buttons to toggle between the USB 1.1 and USB 2.0 modes.

VOLUME (knob)

This motor-driven knob can be turned by hand at any time (even when being driven by the motor).

If HT mode is off, the motor drive will release when the knob is held or turned by hand. If HT mode is on, the motor drive will attempt to return the volume control to the HT setting.


Front Panel Displays

There are sixteen status indicator lights on the front panel. At least one light will be illuminated whenever power is on.

Input Indicators

The input indicators show which input is selected.

A flashing light indicates an error on a digital input.

The HT light shows that HT mode is active.

A1 A solid blue light indicates that analog input A1 is selected.

A2 A solid blue light indicates that analog input A2 is selected.

U A solid blue light indicates that the USB input is selected and operating normally. A blinking blue light indicates that the input is selected but a connection to a computer has not been established.

D1 A solid blue light indicates that optical input D1 is selected and operating normally. A blinking blue light indicates that the input is selected but audio data is not being received.

D2 A solid blue light indicates that optical input D2 is selected and operating normally. A blinking blue light indicates that the input is selected but audio data is not being received.

D3 A solid blue light indicates that coaxial input D3 is selected and operating normally. A blinking blue light indicates that the input is selected but audio data is not being received.

D4 A solid blue light indicates that coaxial input D4 is selected and operating normally. A blinking blue light indicates that the input is selected but audio data is not being received.

Note: D4 cannot be selected if the Digital Pass Through function is enabled. Instructions for configuring this jumper-selected function can be found in the Internal Settings section of this manual.

Input Error Codes

The input indicators flash when errors are present on the selected digital input. There are no error indications for analog inputs. Use the following table to diagnose the problem:

Slow Flash (2Hz)

No digital signal (output muted)

Med. Flash (7Hz)

Data transmission errors or Non-PCM (output muted)

Rapid flashes (14Hz)

Non-audio data is being received (output muted)

Intermittent flashes

Some data corruption is occurring, converter may be interpolating to replace invalid samples, check the cable.

Tip: Common causes of input errors:

• Disconnected or faulty cable • Use of excessively long digital cables • Use of analog cables for digital signals • Use of optical cables for sample rates

exceeding 96 kHz • Incompatible data type (AC3, ADAT, etc.) • Non-audio data is being received

HT Indicator HT A solid light indicates that the HT mode

is active on the selected input and the volume control is in the factory calibrated position (near full clockwise). A blinking light indicates that the HT mode is active but the volume control has not yet reached its calibrated position. The HT light and DIM/MUTE light will blink together if the unit is muted while HT mode is active.


DIM, MUTE, and POLARITY Indicators

DIM/MUTE A solid red light indicates that the unit is in DIM mode. A slow flashing red light indicates that the unit is in MUTE mode. A rapidly flashing red light indicates that the remote control is sending commands.

POLARITY Yellow light indicates that the POLARITY inversion function is active.

Digital Format Indicators

Two lights indicate the measured word length of the selected digital input.

Four lights indicate the sample rate and format of the selected digital input.

Tip: Computers, disk players, and streaming devices often subject the digital signal to sample rate conversion, changes in word length, DSD to PCM conversions, and other forms of digital processing that may degrade the quality of the audio. This display makes it easy to detect these processes.

Word Length Indicators

The 16 and 24 lights indicate the measured word length of the selected digital input. The DAC2 detects active data bits and displays the results as follows:

16 Only Measured input word length is 16 bits.

16 and 24 Measured input word length is 17 to 23 bits.

24 Only Measured input word length is 24 bits.

Both Off Measured input word length is less than 16 bits.

Format indicators

The 44, 48, 2X, 4X, and DSD lights indicate the sample rate and format of the selected digital input as follows:

44 Only The input format is PCM at a sample rate of 44.1 kHz (CD sample rate).

48 Only The input format is PCM at a sample rate of 48 kHz (often used with video).

44 and 2X The input format is PCM at a sample rate of 88.2 kHz (high-resolution audio format).

48 and 2X The input format is PCM at a sample rate of 96 kHz (high-resolution audio format).

44 and 4X The input format is PCM at a sample rate of 176.4 kHz (high-resolution audio format).

48 and 4X The input format is PCM at a sample rate of 192 kHz (high-resolution audio format).

DSD

(4x and 2X)

The input format is 1-bit DSD at a sample rate of 2.8224 MHz (high-resolution audio format). Note: DSD must be streamed in DoP format.

All Off Digital signal is not present or is not in a supported format.


Headphone Jacks

(DAC2 HGC only)

The left-hand jack mutes the XLR and RCA outputs.

The right-hand jack keeps all outputs active.

Headphone Mute Switch

The left-hand headphone jack includes a switch that mutes the main analog outputs (XLR and RCA) when a headphone plug is inserted. This feature allows the listener to switch from loudspeaker to headphone playback seamlessly. This Auto-Mute feature can be disabled with internal jumpers.

Note: Instructions for setting the Auto-Mute jumpers can be found in the Internal Settings section of this manual.

Tip: Use the left-hand jack to mute your loudspeaker system. Use the right-hand jack to keep all outputs active.

Driving Two Sets of Headphones

The HPA2™ is specifically designed with enough power to drive two sets of headphones.

Tip: The Volume Control simultaneously adjusts the level for both jacks. If two listeners will be simultaneously using the headphone outputs, we recommend using headphones with identical or similar voltage sensitivities.

HPA2TM Headphone Power Amplifier

The headphone jacks are driven by Benchmark's HPA2™ headphone power amplifier. This small and very clean power amplifier can deliver the current and voltage required by some of the most demanding headphones. The output impedance of the HPA2™ is very close to 0 Ohms. This low output impedance delivers a high damping factor so that the amplifier can maintain precise control over the headphone transducers.

Headphone voltage sensitivities vary substantially, so we have equipped the HPA2™ with Gain-Range jumpers that can be used to customize the headphone amplifier to your favorite headphones. If you find that you have too much output (volume control set below 11 o'clock), or not enough output (volume control at maximum), there are internal jumpers that can be adjusted to increase or decrease the output level by 10 dB relative to the factory default setting.

Note: Instructions for setting the headphone Gain-Range jumpers can be found in the Internal Settings section of this manual.

Tip: For optimal performance, the headphone Gain-Range jumpers should be set so that comfortable listening levels occur when the volume control is set above the 11 o'clock position.


Operational Details

DIM and MUTE Functions

Definition: If the DIM, MUTE, and HT modes are all off, the DAC2 is in NORMAL mode.

Definition: The NORMAL volume setting is the last volume setting that was in use before the DIM, MUTE, or HT modes were activated.

DIM Function

The DIM function reduces the output level by 20 dB. To toggle between NORMAL and DIM volume, press the DIM button on the remote or the DIM/MUTE button on the front panel.

The red DIM/MUTE light will turn on whenever DIM is active.

When DIM is activated, the NORMAL volume setting is stored in memory while the volume control ramps down by 20 dB. When DIM is deactivated, the volume control ramps back to the NORMAL volume setting that was stored in memory.

The DIM function makes it convenient to fade back and forth between normal and background playback volume levels.

TIP: In the studio, the DIM function allows a temporary reduction in level without losing the volume setting that was being used for monitoring.

Tip: In home applications the DIM function allows temporary reductions in volume during TV commercial breaks, phone calls, or other interruptions, without losing the volume setting that was being used for normal listening.

If the volume is adjusted while DIM is active, it will not change the NORMAL setting unless the DIM volume is turned up above the last NORMAL setting. If the volume control is

turned up by more than 20 dB after DIM is activated, the DIM mode will automatically deactivate, the DIM light will turn off, and the saved NORMAL setting will be replaced by the current volume setting.

DIM cannot be activated when HT mode is enabled.

With digital inputs, DIM will reduce the output level by exactly 20 dB. With analog inputs, DIM will reduce the output level 20 dB +/- 0.5 dB.

MUTE Function

The MUTE function immediately mutes all outputs. To toggle this function, press the MUTE button on the remote or double-tap the DIM/MUTE button on the front panel.

The red DIM/MUTE light will flash at a 1 Hz rate whenever MUTE is active.

When MUTE is activated from a NORMAL listening mode, the audio will immediately mute while the motor-driven volume control ramps down to the -20 dB DIM position. When MUTE is released, the output will unmute at the DIM volume position and then ramp back up to the previous setting. This movement of the motor-driven volume control provides a soft unmute when MUTE is released. It also allows immediate transitions between MUTE and DIM.

Tip: If the unit is in MUTE, press the DIM key to immediately enter the DIM mode.

Tip: If the unit is in MUTE, press the ON key to enter the NORMAL mode.

Tip: if the unit is in DIM, press the MUTE key to toggle between DIM and MUTE.


Bi-directional 12V Trigger

Benchmark has reinvented the 12 volt trigger by adding bidirectional signaling. The trigger connection on the DAC2 can be used as an input, an output, or both. It is compatible with any common 12 volt trigger input or output. The 12V TRIGGER I/O can be used to turn other audio components on when the DAC2 turns on. The DAC2 can also turn on and off in response to other connected components. The Benchmark bi-directional 12V Trigger is compatible with virtually all trigger systems.

The 12V TRIGGER I/O can be connected to the trigger input or output ports on a preamplifier, power amplifier, or both.

The DAC2 can send a 12 Volt DC trigger signal to start other components in the system, or it can wake up in response to an externally generated trigger signal. The DAC2 automatically configures its trigger I/O port as an input (slave) or output (master).

Trigger Output (DAC2 is Master)

When the DAC2 is turned on using the POWER button (on the front panel), or the ON button (on the remote), the DAC2 configures itself as a trigger master and will drive the 12V TRIGGER I/O to 12 volts DC and hold it there while the DAC2 is on. The trigger output signal generated by the DAC2 is delayed so that the DAC2 can stabilize before downstream devices (such as power amplifiers) turn on. When powering down, the DAC2 will mute before allowing the trigger line to drop low. The DAC2 keeps the internal power supplies running for 10 seconds after dropping the trigger. This delay gives other triggered components ample time to mute and shut down.

If the AUTO-ON function is enabled, the DAC2 will automatically turn on when AC power is applied, configure itself as a trigger master, and ignore any external signaling on the 12V TRIGGER I/O line. In AUTO-ON mode, the DAC2 will always drive the 12V

TRIGGER I/O line to 12 V (after a short start-up delay).

Trigger Input - (DAC2 is Slave)

If the DAC2 is off and an external device pulls the trigger I/O to 12 volts, the DAC2 will configure itself as a trigger slave and will follow the actions of the trigger input. The DAC2 will then turn off when the external device stops sending the 12 V trigger.

Typical Trigger Applications

In most systems, the 12V TRIGGER will be used to connect the DAC2 to one other device. The DAC2 can be connected to the first trigger input at the beginning of a trigger chain, or it can be connected to the last trigger output at the end of the chain (less common).

Typical trigger applications:

• DAC2 → Amplifier • DAC2 → Amplifier → Amplifier • DAC2 → Preamplifier → Amplifier • AVR → DAC2, and AVR → Amplifier

(AVR with 2 trigger outputs controls DAC2 and power amplifier)

Trigger Bus Applications

The Benchmark bi-directional trigger system also supports multiple trigger ports wired together on a bus.

A group of Benchmark trigger ports can be connected to a group of non-Benchmark trigger input ports to form a single trigger bus. A bus should never be connected to more than one non-Benchmark trigger output port. If an output port is connected to the bus, this device should be used to start the audio system.

Benchmark AHB2 power amplifiers have two trigger I/O ports that are wired in parallel. This makes it easy to connect more than one power amplifier to a trigger bus. Connect a trigger cable between the DAC2 and the first


amplifier. Use another trigger cable to connect this amplifier to the next amplifier. Any number of Benchmark amplifiers can be added to the trigger bus. The DAC2 will turn on first, and after a delay, all of the amplifiers will turn on together.

Bi-Directional Trigger Applications

Benchmark products support bi-directional communications over a trigger bus. Any Benchmark product connected to the bus can turn the entire system on or off. Because of the bi-directional design, any power button on a Benchmark DAC2 or AHB2 can be used to start or stop the system.

The Benchmark device that starts the system will become the trigger master. If the trigger master is turned off, all slave devices will follow. If a slave device is turned off, all other devices will stay on.

If the DAC2 is used to turn the system on, any connected AHB2 amplifiers will become slave devices and they can be turned off without shutting down the DAC2. This feature makes it easy to turn the AHB2 amplifier(s) off when listening to headphones.

Slave devices can force the entire trigger bus to shut down if the POWER button or OFF button is pressed and held for 3 seconds.

Trigger Specifications

The Benchmark 12V TRIGGER I/O has a wide operating range to allow interfacing with most other DC trigger systems. It should only be used with trigger inputs that are designed to tolerate 12 VDC.

• 12 VDC 200 mA current-limited output • Input responds to 3.3 V logic and

higher • Maximum input voltage = 30 VDC • Maximum reverse input voltage = -0.3

VDC • Input Impedance = 20 k Ohms • 1/8" (3.5 mm) TRS jack • Tip = 12 Volt Trigger I/O • Ring = no connection

• Sleeve = chassis ground

HT Mode

The HT mode sets the volume control to a calibrated level that is near its maximum setting. In HT mode the analog gain is set to 0 dB (unity gain). Likewise the digital attenuation is set to 0 dB (maximum output). The HT light is illuminated when the HT mode is active.

Each input channel can be programmed individually by pressing and holding the mute button for three seconds. In HT mode, analog inputs are passed at unity gain, and digital inputs are passed at maximum gain. The HT mode is similar to the CALIBRATED switch setting on the DAC1 except that it is programmable per input. This flexibility allows seamless integration into home theater systems where the DAC2 handles the main left and right channels.

The HT mode has three distinct applications:

• Volume Control Bypass - useful when the system has an upstream digital volume control or a downstream analog volume control

• Home Theater Bypass - allows high-quality stereo playback on a system that is also used for surround applications

• Calibrated Output - useful in studio applications where calibrated levels are needed

HT Mode - Volume Control Bypass

The HT mode is useful whenever the system volume will be controlled before or after the DAC2. It is usually best to avoid having two cascaded volume controls in a playback system. Dual controls will usually degrade the noise performance of the system and they can lead to confusion.

If the DAC2 feeds a preamplifier, the preamplifier will provide a downstream analog


volume control for the system and the DAC2 should be placed in HT mode for all inputs.

If the DAC2 is directly feeding an amplifier, but one or more sources have volume controls, the sources with volume controls can be set to HT mode.

Example 1: The USB input is fed from a computer that has an internal digital volume control. If you wish to use the volume control in the computer exclusively, you will want to program the USB input with the HT mode on. All other inputs will have the HT mode turned off. If you do not wish to use the computer volume control, leave the HT mode off and disable the computer volume control (or set it to maximum).

Example 2: One of the analog inputs on the DAC2 is fed from a preamplifier with an analog volume control that you wish to use. Set this analog input to HT mode on.

HT Mode - Home Theater Bypass

The home theater bypass is useful when you have a home theater system that will also be used for playing stereo recordings. The DAC2 will directly drive the left and right power amplifiers while the AVR drives all other speakers. The analog left and right line-level outputs of the AVR will be connected to one set of analog inputs on the DAC2 (usually A1). Stereo sources will be connected directly to the digital inputs on the DAC2. Surround sources will be connected directly to the inputs on the AVR.

When playing stereo recordings, digital feeds are sent directly to the DAC2 and the volume control on the DAC2 is used to control the playback level (HT mode must be off on all digital inputs). This configuration gives the best-possible performance for stereo applications because it eliminates the AVR from the stereo playback chain. If the stereo system includes a turntable and an outboard phono preamplifier, the outputs of the phono preamplifier can be connected directly to the second set of analog inputs on the DAC2 (HT mode off, analog input A2).

When playing movies and other surround sources, analog signals from the AVR would pass through the DAC2 at unity gain (HT mode on, analog input A1).

For stereo applications, digital sources would feed the DAC2 and the volume control on the DAC2 would control the playback level (HT mode off, digital inputs).

HT Mode – Calibrated Output

Any digital input can be set to a factory-calibrated fixed-gain by turning the HT mode on. In HT mode, the digital audio output is set to a fixed audio level. This mode is useful in studio applications where calibrated interface levels are used between various pieces of equipment. (Note: This function is similar to the calibrated mode on the DAC1.)

USB MODE Selection

The DAC2 supports two USB MODES:

• USB Audio 1.1 mode - up to 24 bits at 96 kHz

• USB Audio 2.0 mode - up to 24 bits at 192 kHz plus DSD in DoP 1.1 format

Caution: Close all USB audio playback applications before changing the USB MODE. If an audio application is playing while the USB MODE is changed, the audio application may freeze.

Note: The computer and DAC2 must be connected and both must be on before the USB MODE can be changed.

To change the USB MODE, select the USB (U) input on DAC2 and then press and hold the USB button on the remote control for 3 seconds. If a remote control is not available, simultaneously press and hold both INPUT buttons on the front panel for 3 seconds.

After holding the button(s) for 3 seconds, either the 4X lamp or the 2X lamp will flash


once indicating the new USB MODE. A flash of the 4X lamp indicates that the unit is now in USB Audio 2.0 mode. A flash of the 2X lamp indicates that the unit is now in USB Audio 1.1 mode.

Tip: The 4X or 2X lamp will flash once every time the USB input is selected. This flash provides a convenient indication of the current USB MODE.

Tip: Avoid any unnecessary switching between USB MODES. Rapid switching between modes can confuse some operating systems.

Driving Power Amplifiers

The DAC2 is designed to directly drive virtually any audio power amplifier or powered monitor. This direct connection provides the cleanest and shortest path from the digital source to the monitor output.

Tip: Benchmark does not recommend placing audio devices between the DAC2 and the power amplifier unless these devices are providing an indispensible system function. A direct connection between the DAC2 and the power amplifier will always provide the best system-level performance (SNR and THD+N).

The RCA and XLR outputs on the DAC2 are equipped with low-impedance high-current drivers. These robust outputs are well equipped to drive a wide variety of input impedances. The DAC2 outputs remain clean when driving amplifiers that present difficult loads (high input capacitance and/or low input impedance).

The XLR outputs on the DAC2 are equipped with jumper-configured passive low-impedance output pads. These pads can be set to an attenuation of 0 dB (pad off), 10 dB, or 20 dB. The pads should be used to match the output level of the DAC2 to the input sensitivity of the power amplifier. Most power amplifiers and powered monitors will require the use of the 10 dB or 20 dB pads.

Use the 0 dB setting when driving a Benchmark AHB2 power amplifier.

Tip: The Benchmark AHB2 power amplifier has a unique low-gain topology that allows it to accept full studio-level input signals. This high-level interconnection provides a very low-noise connection between the DAC2 and the AHB2. Set the input SENSITIVITY switch on the AHB2 to 22 dBu (all the way down). This places the AHB2 full-power output point at an input level of 22 dBu. This level is exactly 2 dB lower than the maximum output level of the DAC2 (when the pads are set to 0 dB). This configuration optimizes the gain-staging between the DAC2 and the AHB2 while placing the DAC2 volume control in the proper range.

Tip: If you are using a DAC2 with non-Benchmark power amplifiers, the XLR pads should be set so that comfortable listening levels occur when the VOLUME control is set above 11 o’clock. This will optimize the gain-staging between the DAC2 and your power amplifier.

Tip: Increase the pad setting if a comfortable listening level is reached at a VOLUME control setting below the 11 o'clock position.

Tip: Decrease the pad setting if a comfortable listening level cannot be reached when the VOLUME control is fully clockwise.

Instructions for setting the XLR pad jumpers are detailed in the Internal Settings section of this manual. The DAC2 is shipped with the XLR pads disabled (set to 0 dB). No adjustments will be necessary if you will be using a Benchmark AHB2 power amplifier.

HPA2™ Headphone Amplifier

(DAC2 HGC model only)

The left headphone jack has a mute switch that mutes all of the analog outputs on the back of the DAC2. The right headphone jack does not have a mute switch. The audio output on both jacks is wired in parallel and is driven


by Benchmark's HPA2™ headphone power amplifier.

The HPA2™ is one of the most transparent headphone amplifiers available. It also is able to deliver high current and/or high signal levels making it well suited for a wide variety of headphones. The near 0-Ohm output impedance provides outstanding damping of headphone drivers. This damping reduces distortion while maintaining precise control of the frequency response at the output of the amplifier.

Digital Pass-Through

The second coaxial input (D4) can be reconfigured as a digital output. When operating as an output, any selected digital input is passed through to D4 without any processing.

Optical, coaxial, and USB inputs (U, D1, D2 and D3) can be passed through to the D4 connector. The signals are buffered but are not processed in any way. For this reason, any data format can be passed through to the D4 connector, even when these formats cannot be decoded by the DAC2. Surround formats such DTS, Dolby Digital, cannot be decoded by the DAC2, but they can be passed to a surround system using the digital pass-through function.

The digital pass-through can also be used to provide the following digital signal conversions:

• Optical to Coaxial • USB to Coaxial • Coaxial to Coaxial (buffering)

DoP encapsulated DSD can also be passed through D4. DSD files on a computer can be sent in DoP to the USB input on the DAC2. The USB input can be routed to coaxial output D4. This output can be recorded by any 24-bit, 176.4 kHz digital recorder with a coaxial input. The PCM digital recorder can then be used to play the DSD recordings.

Firmware Version Identification The firmware version is displayed during the lamp test while the DAC2 is turning on. At least one lamp in the INPUT INDICATOR will flash rapidly while the remaining lamps will be on. The flashing lamps identify the firmware version. The values of each lamp

are shown in this chart. Add the values of all flashing lamps to determine the version number.

Rear Panel

DAC2 HGC and DAC2 L

Digit 1 Digit 2 8 D1 D2 .8 4 U D3 .4 2 A2 D4 .2 1 A1 HT .1


Inputs

There are seven stereo inputs on the DAC2:

• A1 - RCA L & R Analog Inputs • A2 - RCA L & R Analog Inputs • USB - USB Audio 1.1 or 2.0 Input • D1 - Optical Digital Input • D2 - Optical Digital Input • D3 - Coaxial Digital Input • D4 - Coaxial Digital Input or Output*

These inputs are selected using the INPUT buttons on the front-panel or on the remote-control.

* D4 can be jumper-configured as a digital PASS-THROUGH output. When enabled, the selected digital input will be routed to the internal D/A converter and to output D4. The selected input will be buffered and sent to output D4 even if the format cannot be decoded by the DAC2.

The digital inputs support PCM stereo AES/EBU and SPDIF digital formats. Maximum word length is 24-bits. Maximum sample rate is 192kHz.

The digital inputs also support DSD stereo at a sample rate of 2.8224 MHz using DoP 1.1 encapsulation.

The USB input has two operating modes:

• USB Audio 1.1 - PCM up to 24-bits at 96 kHz

• USB Audio 2.0 - PCM up to 24-bits at 192 kHz and DSD (DoP 1.1 format)

Caution: The optical inputs (D1 and D2) are not recommended for DSD or for sample rates above 96 kHz. Optical connections may be unreliable at sample rates above 96 kHz.

Tip: The DAC2 will not decode multichannel digital formats such as AC3, and Dolby Digital. The audio will mute and the INPUT INDICATORS will flash whenever an incompatible format is connected to the selected digital input. If the PASS-THROUGH mode is enabled, these multichannel formats can be sent to a surround processor using connector D4 as a digital output.

Caution: The 12V TRIGGER I/O is not an audio connection! This is a 12V DC connection for synchronizing the on and off sequencing of an entire audio system.


Analog Inputs – RCA Unbalanced

The DAC2 has two sets of unbalanced stereo analog inputs with female RCA connectors.

The analog inputs can be used for devices such as:

• Phono preamplifiers • FM Tuners • Tape Transports • Analog VCR outputs • iPod and MP3 devices • Outputs from analog mixing consoles

Digital Inputs - Overview

All of the digital inputs on the DAC2 use Benchmark's UltraLock2™ system to remove virtually all of the interface jitter. The result is that all digital inputs deliver identical audio performance. The USB, optical, and coaxial digital inputs will all sound identical if they receive identical data.

Computer Input – USB

The USB input accepts a Type-B male USB connector. A Type-A to Type-B USB cable is provided with the DAC2. The USB cable connects the DAC2 directly to a computer’s USB output.

The USB input supports 44.1, 48, 88.2, 96, 176.4, and 192 kHz PCM sample rates at word lengths up to 24-bits. The USB input also accepts DSD in DoP 1.1 format.

The DAC2 can be configured as a USB Audio 1.1 or USB Audio 2.0 device. Press and hold the USB button on the REMOTE for three seconds to toggle the USB MODE. If a remote is not available, simultaneously press and hold both input buttons on the front panel for three seconds.

The USB AUDIO 1.1 mode does not require the installation of a driver. It allows a quick driverless connection to windows machines when playing sample rates of 96 kHz or less. In this mode, Windows machines can begin

streaming audio within seconds after the DAC2 is connected for the first time. No software or hardware configuration is usually required.

USB Audio 2.0 is required for DSD and for all PCM sample rates exceeding 96 kHz. Windows computers require a driver to support the USB Audio 2.0 mode.

The USB Audio 1.1 mode was tested for compatibility with Windows XP, Vista, 7, 8 and 10, Mac OS X, and iPads using the 30-pin to USB Camera Kit. No driver installation is required for any of these systems when operating in USB Audio 1.1 mode.

The USB Audio 2.0 mode was tested for compatibility with Windows XP, Vista, 7, 8 and 10 (driver installation is required for all Windows versions). It was also tested for compatibility with Mac OS X starting with version 10.6 (operation is driverless for all OS X versions).

Optical Digital Inputs - D1 and D2

The optical input connectors (D1 and D2) are commonly known as TOSLINK connectors. The TOSLINK optical connectors used on the DAC2 are designed to work well at sample rates up to 96 kHz. Maximum word length is 24-bits. All sample rates between 28 and 96 kHz are supported. The optical inputs may be unreliable at sample rates above 96 kHz. The optical inputs will accept professional AES/EBU data formats or consumer S/PDIF data formats.

Tip: The optical inputs include dust caps. Keep these in place if the input is not being used.


Coaxial Digital Inputs - D3 and D4

The coaxial digital inputs (D3 and D4) use female RCA connectors. The input impedance is 75 Ohms. Maximum word length is 24-bits. All sample rates between 28 and 195 kHz are supported. The coaxial digital inputs will accept professional AES/EBU data formats or consumer S/PDIF data formats. The coaxial inputs also accept DSD in DoP 1.1 format.

The coaxial digital inputs are DC isolated, current limited, and diode protected. The RCA body is bonded directly to the chassis to prevent currents in the internal ground system. This direct bonding also maximizes RF shielding.

Caution: Use 75-Ohm coaxial cables for digital audio connections D3 and D4. Digital interfaces require the use of matched impedances. Do not use 50-Ohm coaxial cables, twisted pair cables, or any non-coaxial cables for digital audio. The digital inputs may not function, or may be unreliable if the incorrect cable is used.

Tip: The RCA analog inputs and outputs have no restrictions on cable type. To avoid confusion, we recommend using 75-Ohm coaxial cables for all RCA connections. 75-Ohm coaxial cables are compatible with digital audio, analog audio, and video.

Note: The Coaxial inputs (D3 and D4) accept professional or consumer digital audio formats. The AES3-id and SMPTE 276M standards specify a 75-Ohm, 1 Vpp, professional format which is also known as AES/EBU and is commonly used in video production facilities. The IEC 609588-3 standard specifies a 75-Ohm, 0.5 Vpp, consumer format which is also known as S/PDIF, and is commonly used in hi-fi equipment. The coaxial inputs are designed to accept either type of signal.

12V TRIGGER I/O

The Benchmark bi-directional 12V TRIGGER is compatible with virtually all trigger systems. The 12V TRIGGER I/O connection

on the DAC2 can be used as an input, an output, or both. It is compatible with most 12 volt trigger inputs and outputs. The 12V TRIGGER can be used to turn other audio components on when the DAC2 turns on. The DAC2 can also turn on and off in response to trigger signals sent from other components.

The 12V TRIGGER I/O can be connected to the trigger input or output ports on a preamplifier, power amplifier, or both.

The DAC2 can send a 12 Volt trigger signal to start other components in the system, or it can wake up in response to an externally generated trigger signal. The DAC2 automatically configures the 12V TRIGGER I/O port as an input (slave) or output (master). See the Bi-directional 12V Trigger section for more information.

The Benchmark 12V TRIGGER I/O has a wide operating range to allow interfacing with most other DC trigger systems. It should only be used with trigger inputs that are designed to tolerate 12 VDC.

• 12 VDC 200 mA current-limited output • Input responds to 3.3 V logic and

higher • Maximum input voltage = 30 VDC • Maximum reverse input voltage = -0.3

VDC • Input Impedance = 20 k Ohms • 1/8" (3.5 mm) TRS jack • Tip = 12 Volt Trigger I/O • Ring = no connection • Sleeve = chassis ground

Caution: The 12V TRIGGER I/O is not an audio connection! This is a 12V DC connection for synchronizing the on and off sequencing of an entire audio system.


Outputs

Analog Outputs

The DAC2 has one pair of balanced XLR outputs and two pairs of unbalanced RCA outputs.

The DAC2 features high-current output drivers that are capable of driving 300-Ohm loads without an increase in distortion. They are also well suited for driving long cables or high-capacitance loads.

Balanced XLR Analog Line Outputs

The Left and Right balanced outputs use Neutrik™ gold-pin male XLR jacks. The XLR shell and pin 1 (ground) are both directly bonded to the chassis to prevent currents in the internal ground system. This direct bonding also maximizes RF shielding.

The XLR outputs have passive attenuators that allow direct connections to a wide variety of audio devices without a loss of dynamic range. The 10 or 20 dB pads are usually required for direct interfacing to power amplifiers and powered speakers. The DAC2 ships with the pads disabled (0 dB setting). Use the 0 dB setting with the Benchmark AHB2 power amplifier. A full description of the output attenuators and instructions for

configuration is located in the Internal Settings section of this manual.

Industry-Standard XLR Wiring

• XLR pin 2 = + Audio Out • XLR pin 3 = - Audio Out • XLR pin 1 = Cable Shield

Caution: If the balanced XLR outputs are wired to an unbalanced input (using a special adapter cable), pin 3 must be left floating. Shorting pin 3 to ground will increase the temperature of the output drivers, will increase power consumption, and may cause distortion.

Unbalanced RCA Analog Outputs

The Left and Right unbalanced outputs use female RCA jacks. The ground connections are bonded to chassis ground at the location where analog ground is bonded to the chassis. This minimizes the effects of ground loops caused by AC currents in the cable shield. The RCA output impedance is very low (30 Ohms). This makes these outputs well suited for driving high-capacitance loads and/or high-capacitance cables.

Caution: Mono summing with an RCA ‘Y’ cable is not recommended as this will cause high amounts of distortion. Mono summing with a ‘Y’ cable can be accomplished with the use of a modified cable by implementing a 1k Ohm series resistor in each leg of the ‘Y’.

Note: The XLR pads do not have any effect on the level of the RCA outputs.


AC Power-Entry and Fuse Module

Input Voltage Range

Note: The DAC2 is equipped with a universal power supply. There is no voltage selection switch. AC voltage range is 88-264 VAC, 50-60 Hz. The product may also be operated from DC power over a voltage range of 125-373 VDC.

Power Cord

Note: The AC power input uses a standard IEC type connector. One USA-compatible power cord is included with DAC2 converters. IEC style power cords in country-specific configurations are available in your locality.

Caution: Always use a grounded power cord. The DAC2 is equipped with a standard IEC power entry module. Use an IEC power cord that is equipped with the appropriate connector for your location. Cords are available from your dealer.

Fuses

Caution: For continued fire hazard protection always replace the fuses with the correct size and type (0.5A 250 V Slo-Blo® 5 x 20 mm – Littelfuse® HXP218.500 or equivalent). The fuse drawer includes two fuses. Always replace both fuses at the same time.


Internal Settings

Jumper-Configured Options

The following functions are jumper configured:

• XLR Output Pads • Headphone Mute Switches • Headphone Gain • Digital Pass-Through

Removing Top Cover

The DAC2 cover must be removed to gain access to the jumpers. Do not attempt to remove the faceplate or rear panel.

Caution: The DAC2 contains static sensitive components. Static discharge may cause component failures, may affect the long-term reliability, or may degrade the audio performance. Use a static control wrist strap when changing jumper settings.

• Disconnect AC power by unplugging the power cord at the back of the DAC2.

• Remove the 8 screws holding the cover (4 on each side).

• Do not remove any screws on the front, rear, or bottom panels!

• Never remove the power entry safety cover in the rear corner of the DAC2.

• Always connect a static-control wrist strap to the chassis before touching any internal component.

XLR Output Pads

The XLR outputs are equipped with low-impedance passive pads that may be used to reduce the output levels while preserving the full dynamic range of the DAC2. The DAC2 ships with the pads disabled (0 dB setting).

Tip: Use the 0 dB setting with Benchmark's AHB2 power amplifier. When directly driving other power amplifiers or powered speakers, start with the 10 dB pad setting. If necessary, change the pads so that normal listening levels are achieved with the VOLUME control above the 11 o’clock position.

When the output pads are enabled, the output impedance changes slightly, and the maximum allowable cable length should be reduced as shown in Table 1 (assuming 32 pF/foot and a maximum allowable loss of 0.1 dB at 20 kHz).

Table 1 - Cable Drive Capability

Balanced Output Drive Capability:

Attenuator Output Maximum Loss in dBSetting (dB) Impedance Cable (ft) at 20 kHz

0 60 680 0.110 425 96 0.120 135 302 0.1

Unbalanced Output Drive Capability:

Output Maximum Loss in dBImpedance Cable (ft) at 20 kHz

30 1360 0.1

Tip: To set the XLR outputs to typical professional studio levels, set the pads to 0 dB. For most home installations, set the pads to 10 dB or 20 dB.


XLR Output Pad Jumpers

Four jumpers on four 6-pin headers (P8, P9, P10, and P11) allow selection of the output level at the XLR jacks. The jumpers are properly configured if a normal playback level is achieved when the VOLUME control is set above the 11 o'clock position.

One pair of 6-pin headers control the attenuation at each XLR jack as follows:

• 0 dB - (Attenuator disabled) – (Jumper plug between pins 1 and 2 of each header) - Factory Default

• -10 dB – (Jumper plug between pins 3 and 4 of each header)

• -20 dB – (Jumper plug between pins 5 and 6 of each header)

Figure 1 - Attenuators set to -10 dB

Headphone Switch Configuration

(DAC2 HGC only)

The left-hand headphone jack is equipped with a switch that will mute the analog outputs when a headphone plug is inserted. The right-hand headphone jack does not have a mute switch. In most cases it is convenient to have one jack that mutes the outputs and

on that does not mute the outputs. If your requirements are different the HEADPHONE SWITCH can be defeated.

Headphone Switch Disable

The HEADPHONE SWITCH on the left-hand headphone jack can be defeated by adding jumpers at JP1 and JP2.

• HEADPHONE SWITCH enabled (no jumpers at JP1 or JP2) - Factory Default

• HEADPHONE SWITCH disabled (jumpers installed at JP1 and JP2)

Figure 2 - Headphone Switch Enabled (Factory Default)

Figure 3 - Headphone Switch Disabled


Headphone Amplifier Gain

(DAC2 HGC only)

The gain range of the HPA2™ can be set using jumpers JP3 and JP4:

• 0 dB attenuation - see Figure 4 • 10 dB attenuation - see Figure 5

(Factory Default) • 20 dB attenuation - see Figure 6

The attenuation is inserted before the HPA2™ headphone amplifier. This attenuator location keeps the output impedance of the HPA2™ constant and very near 0 Ohms. External attenuators should never be inserted after a headphone amplifier as this would change the output impedance.

Proper attenuator settings are important for maximizing the SNR of the headphone monitoring system. With proper settings, the full performance of the DAC2 can be delivered to the headphones for critical monitoring tasks, or maximum musical enjoyment.

Tip: When the headphone attenuation jumpers are set properly, a normal listening level will be achieved at a VOLUME control setting above the 11 o'clock position.

Tip: If a normal listening level is achieved below an 11 o’clock VOLUME setting, the headphone gain is too high, and the attenuation should be increased.

Tip: If the level is too low at the maximum VOLUME setting, the headphone gain is too low, and the attenuation should be decreased.

Figure 4 - 0 dB Headphone Attenuation




Digital PASS-THROUGH Function

The digital PASS-THROUGH function can be enabled by moving both P14 jumpers toward the faceplate shown in Figure 7. Once the jumpers are moved into the position shown in Figure 7, D4 is configured as a digital audio output. When the PASS-THROUGH function is enabled, D4 cannot be selected as an input. Any other selected digital input will be routed to both the internal D/A converter and to output D4. The digital output at D4 is buffered, but is not processed. Many digital audio formats can be passed through to D4 (even when these formats cannot be decoded by the DAC2).

By default, D4 functions as a digital input and the jumpers are set according to Figure 8.

Figure 7 – Digital PASS-THROUGH Enabled

Figure 8 - Digital PASS-THROUGH Disabled (Factory Default)


Rack Mounting

An optional rack mount tray allows the mounting of any two ½-wide Benchmark products in a single rack space. A blank plate can be added when only one unit is installed in the rack mount tray.

The Benchmark Rack Mount Tray and Benchmark ½-Wide Blank Plate are available from Benchmark.

Benchmark Rack Mount Tray

The Benchmark Rack Mount Tray mounts up to two ½-wide Benchmark products in a single race space. The tray accepts any combination of ½-wide Benchmark products (with or without rack-mount type faceplates).

Benchmark ½-Wide Blank Plate

The Benchmark ½-Wide Blank Plate is a ½-wide 1-RU anodized aluminum panel for covering an unused slot in the Benchmark Rack Mount Tray. It is available in black or silver.

Visit BenchmarkMedia.com for a complete selection of cable, accessories, and replacement parts.

http://www.benchmarkmedia.com/


Benchmark Technologies

DAC1 and DAC2 Family History

The pristine audio performance of the award-winning DAC1 made it the ‘Benchmark’ of stand-alone D/A converters. The DAC1 USB, DAC1 PRE , and DAC1 HDR added many features to the basic DAC1 platform. Benchmark DAC1 and DAC2 converters are in use in many of the world's top studios.

The following is a brief overview of the various Benchmark DAC1 and DAC2 models:

DAC1

Benchmark's original DAC1 converter.

The DAC1 features included:

• Three digital inputs • XLR outputs with passive pads • RCA outputs • Analog volume control • HPA2™ headphone amplifier • UltraLock™ jitter-attenuation system

DAC1 USB

The DAC1 USB introduced these improvements:

• AdvancedUSB™ computer input • Mute switch on the left headphone jack • Two headphone gain ranges • High-current LM4562/LME49860 output

stages - designed to drive difficult loads • Lower output impedances

Benchmark's AdvancedUSB™ computer input was the first USB audio interface to support 96 kHz audio without the need to install special drivers.

DAC1 PRE

The DAC1 PRE added these improvements:

• Three coaxial digital inputs • Three Headphone Gain Ranges • LM4562/LME49860 opamps throughout • Premium bulkhead-mounted RCA

connectors

The DAC1 PRE eliminated the XLR digital input found on the DAC1 and DAC1 USB.

DAC1 HDR

The DAC1 HDR added these improvements:

• IR Remote Control • HDR-VC™ (high dynamic range

volume control).

The HDR-VC™ features a custom-made, motor-driven Alps potentiometer. The motor-driven control provides the audio performance of a manual control while adding the convenience of remote control.

DAC2 HGC

The DAC2 maintains the familiar DAC1 form factor, but internally, it is a complete redesign. The DAC2 features:

• Four 32-bit D/A per output channel • Native 24-bit/192kHz PCM conversion • Native DSD conversion • Multi-mode asynchronous USB audio

input • Sample rate and word length displays • UltraLock2™ jitter attenuation • Polarity control • Home theater bypass • Digital pass-through • Bi-directional 12V trigger • Two stereo analog inputs • Three stereo analog outputs • Two optical inputs • High-efficiency low-noise power

supplies


Hybrid Gain Control™

HGC™ is Benchmark's unique Hybrid Gain Control™ system. The DAC2 combines active analog gain control, passive low-impedance attenuators, a 32-bit digital gain control, and a servo-driven volume control.

All inputs are controlled by the rotary volume control. This volume control moves in response to commands from the remote control. Analog inputs are never converted to digital, and digital inputs never pass through an analog potentiometer. Digital inputs are precisely controlled in the 32-bit DSP system. The DSP system preserves precise L/R balance, and precise stereo imaging, while avoiding any source of noise and distortion.

Benchmark's unique passive output attenuators provide distortion-free gain reduction without reducing the dynamic range of the converter. The attenuators optimize the gain staging between the DAC2 and the power amplifier. This optimization is absolutely essential for maximizing the dynamic range of the entire playback system. Much of the success of the DAC1 and DAC2 converters can be attributed to the passive output attenuators. Musical details can be obscured by system noise whenever a preamplifier and power amplifier are improperly matched. The HGC™ system will make full use of your power amplifier's dynamic range. Experience newly revealed details in your favorite recordings.

The front-panel volume control is a servo-driven gain control built around a custom-made Alps potentiometer. The custom Alps pot is equipped with remote-controllable motor drive.

This potentiometer is equipped with a clutch which prevents damage from overriding the motor drive. If the pot is driven beyond the end of its range, it will not damage the motor. Also, if the pot is manually overridden, it will not damage the motor.

Native DSD Conversion

The digital coaxial inputs and the USB Audio 2.0 input on the DAC2 support native DSD conversion. DoP 1.1 DSD encapsulation is automatically detected on all digital inputs. The system seamlessly switches to native DSD conversion when DoP is detected. DoP 1.1 DSD encapsulation is supported by many media players. DSD downloads are now available from several sources.

Visit our website for an up-to-date list of DSD and PCM high resolution download sites.

Jitter-Immune UltraLock2™

UltraLock2™ is an improved version of the UltraLock™ system used in the DAC1 product family. DSP processing is 32-bits, DSP headroom is 3.5 dB, sample rate is 211 kHz, and jitter-induced distortion and noise is at least 160 dB below the level of the music - well below the threshold of hearing. Benchmark's UltraLock2™ system eliminates all audible jitter artifacts.

High Headroom DSP

All of the digital processing in the DAC2 is designed to handle signals as high as +3.5 dBFS. Most digital systems clip signals that exceed 0 dBFS. The 0 dBFS limitation seems reasonable, as 0 dBFS is the highest sinusoidal signal level that can be represented in a digital system. However, a detailed investigation of the mathematics of PCM digital systems will reveal that inter-sample peaks may reach levels slightly higher than +3 dBFS while individual samples never exceed 0 dBFS. These inter-sample peaks are common in commercial releases, and are of no consequence in a PCM system until they reach an interpolation process. But, for a variety of reasons, virtually all audio D/A converters use an interpolation process. The interpolation process is absolutely necessary to achieve 24-bit state-of-the art conversion performance. Unfortunately, inter-sample overs cause clipping in most interpolators.


This clipping produces distortion products that are non-harmonic and non-musical. We believe these broadband distortion products often add a harshness or false high-frequency sparkle to digital reproduction. The DAC2 avoids these problems by maintaining at least 3.5 dB of headroom in the entire conversion system. We believe this added headroom is a groundbreaking improvement.

32-bit SABRE Conversion System

Four balanced 32-bit D/A converters deliver audio to Benchmark's low-impedance current to voltage converters. The 4:1 redundancy reduces noise by 6 dB. The redundancy also reduces the THD. The conversion system at the core of the DAC2 is as good as it gets. The analog circuits that follow the D/A converter are carefully designed. Benchmark has leveraged its long history of building reference analog audio equipment to create an outstanding output stage.

Diagnostic Displays

Ever wonder why that 192 kHz 24-bit download on your computer just doesn't sound right? Your media player or computer may be downsampling to 44.1 kHz and/or truncating to 16-bits. Many media players and computer operating systems apply poor-quality sample rate conversion and/or truncation. Fortunately these problems can be eliminated with the selection of a good frequency-agile media player.

Many disk players also downsample all sources to 44.1/16. This processing can do significant damage to the audio quality.

The sample-rate and word-length displays on the DAC2 confirm the proper operation of your disk player, media player, and computer.

Bi-Directional 12 Volt Trigger

Benchmark has re-invented the 12 volt trigger. The trigger connection on the DAC2

can be used as an input or output or both, and is compatible with any common 12 volt trigger input or output. The trigger can be used to turn a power amplifier on or off automatically. The DAC2 will also respond to a 12 volt trigger and follow the actions of another audio component.

Benchmark components can communicate bi-directionally on the trigger I/O ports. This bidirectional communication provides greater flexibility. In a given system, the power button on any Benchmark device can be used to start or stop the entire audio system in a sequenced manner.

Distributed Power Regulation

To achieve the lowest possible noise, the DAC2 uses distributed power supply regulation. Each critical subsystem has at least one dedicated low-noise voltage regulator.

We have created a discrete ultra low-noise regulator for the ES9018 D/A converter. This Benchmark exclusive feature improves the noise performance of the already-outstanding ES9018.

HPA2™ Headphone Amplifier The DAC2 headphone output is driven by Benchmark’s signature HPA2™ headphone power amplifier. This high-current, high-output amplifier has an output impedance of near 0-Ohms. It is designed to drive loads as low as 30 Ohms without any increase in distortion. It also has sufficient amplitude to drive low-sensitivity 600-Ohm headphones. The HPA2™ includes current-limiting circuits that fully protect against damage from short circuits. This is important because the right channel of a headphone amplifier will experience a short whenever a mono phone plug is inserted into the stereo headphone jack. Shorts may also occur when a plug is partially inserted.


0-Ohm Output Impedance Most headphone amplifiers use series resistors to maintain stability and protect against short-circuit conditions. These resistors are usually at least 30 Ohms, and have a negative impact on performance. A headphone amplifier with series resistors may measure very well on a test bench when driving resistive loads. However, the same amplifier will measure very poorly when driving a headphone load. Unfortunately, most manufacturers do not measure or specify headphone amplifier performance when loaded with real headphones. The measurements use ideal resistive loads. Our measurements show that headphones do not behave like resistive loads.

Headphone Performance In our tests we have measured substantial distortion across resistors that are wired in series with headphones. We have conducted measurements with a variety of headphones. In general, distortion increases as headphone impedance decreases. This distortion can be eliminated with a properly designed 0-Ohm headphone amplifier. The performance of the HPA2™ does not change when headphones are driven. THD+N measurements for no-load, 30-Ohm resistive loads, 30-Ohm headphone loads, and 600-Ohm headphone loads are virtually identical. The HPA2™ will substantially improve the sound of 30 and 60-Ohm headphones. It will make very noticeable improvements with 600-Ohm headphones. Differential Amplifiers

Differential amplifiers remove common-mode distortion components from the D/A converter outputs. This feature is critical for achieving low-distortion in down-stream devices. Benchmark addresses common-mode distortion so that it will not cause distortion in power amplifiers and other connected devices. Common-mode distortion can cause audible distortion while escaping the scrutiny of an audio analyzer. The balanced and

unbalanced outputs on the DAC2 deliver very similar performance.

Many D/A converters omit the differential amplifiers after the converters. Specifications usually ignore common-mode distortion. A balanced signal with high common-mode distortion can measure just fine when feeding a precisely balanced input on a high-quality audio analyzer. However, any imbalance in a downstream device will expose the common-mode distortion.

UltraLock2™ Clock System

Accurate 24-bit audio conversion requires a very low-jitter conversion clock. Jitter can very easily turn a 24-bit converter into a 16-bit converter (or worse). There is no point in buying a 24-bit converter if clock jitter has not been adequately addressed.

Jitter is present on every digital audio interface. This type of jitter is known as ‘interface jitter’ and it is present even in the most carefully designed audio systems. Interface jitter accumulates as digital signals travel down a cable from one digital device to the next. If we measure interface jitter in a typical system we will find that it is 10 to 10,000 times higher than the maximum allowable level for accurate 24-bit conversion. Fortunately, interface jitter has absolutely no effect on the audio unless it influences the conversion clock in an analog-to-digital converter (A/D), the conversion clock in a digital-to-analog converter (D/A), or the rate estimator in an asynchronous sample rate converter (ASRC).

Many converters use a single-stage Phase Lock Loop (PLL) circuit to derive their conversion clocks from AES/EBU, wordclock, or superclock reference signals. Single-stage PLL circuits provide some jitter attenuation above 5 kHz but none below 5 kHz. Unfortunately, digital audio signals often have their strongest jitter components at 2 kHz. Consequently, these converters can achieve their rated performance only when driven from very low jitter sources and through very


short cables. It is highly unlikely that any converter with a single-stage PLL can achieve better than 16 bits of performance in a typical installation. Specified performance may be severely degraded in most installations.

Better converters often use a two-stage PLL circuit to filter out more of the interface jitter. In theory, a two-stage PLL can remove enough of the jitter to achieve accurate 24-bit conversion (and some do). However, not all two-stage PLL circuits are created equal. Many two-stage PLLs do not remove enough of the low-frequency jitter. In addition, two-stage PLL circuits often require several seconds to lock to an incoming signal. Two-stage PLL circuits may fail to lock when jitter is too high, or when the reference sample frequency has drifted.

UltraLock™ converters exceed the jitter attenuation performance of two-stage PLL converters while achieving near instantaneous lock time. They are free from the slow-lock and no-lock problems that can plague two-stage PLL designs. UltraLock™ converters have extremely high immunity to interface jitter under all operating conditions.

The UltraLock™ system is so effective that no jitter-induced artifacts could be detected using an Audio Precision System 2 Cascade test set while the inputs to the DAC2 were exposed to high levels of interface jitter. The measurement limits included the ability to detect artifacts as low as –144 dBFS, but none could be detected, even while applying jitter amplitudes as high as 12.75 UI, over a frequency range of 2 Hz to 200 kHz. Any AES/EBU signal that can be decoded by the AES/EBU receiver in the DAC2 will be reproduced without the addition of any measurable jitter artifacts.

Benchmark’s UltraLock2™ technology eliminates jitter-induced performance problems. UltraLock2™ technology isolates the conversion clock from the digital audio interface clock. Jitter on a D/A digital audio input, or an A/D reference input can never have any measurable effect on the conversion clock of an UltraLock2™ converter. In an

UltraLock2™ converter, the conversion clock is never phase-locked to a reference clock. Instead the converter oversampling-ratio is varied with extremely high precision to achieve the proper phase relationship to the reference clock. The clock isolation of the UltraLock2™ system ensures that interface jitter can never degrade the quality of the audio conversion. Specified performance is consistent and repeatable in any installation with cables of any quality level!

How does conversion clock jitter degrade converter performance? Problem #1: Jitter phase-modulates the audio signal. This modulation creates sidebands (unwanted tones) above and below every tone in the audio signal. Worse yet, these sidebands are often widely separated from the tones in the original signal.

Jitter-induced sidebands are not musical in nature because they are not harmonically related to the original audio. Furthermore, these sidebands are poorly masked (easy to hear) because they can be widely separated above and below the frequencies of the original audio tones. In many ways, jitter induced distortion resembles intermodulation distortion (IMD). Like IMD, jitter induced distortion is much more audible than harmonic distortion, and more audible than THD measurements would suggest.

Jitter creates ‘new audio’ that is not harmonically related to the original audio signal. This ‘new audio’ is unexpected and unwanted. It can cause a loss of imaging, and can add a low and mid frequency ‘muddiness’ that was not in the original audio.

Jitter-induced sidebands can be measured using an FFT analyzer while the converter plays a pure high-amplitude tone. We typically use a full-scale 10 kHz test tone to test for the presence of jitter-induced side bands (see Plot 15). This FFT shows that the DAC2 is free from any jitter-induced sidebands to a measurement limit of about -144 dB relative to the level of the test tone.


The plot used 31 different jitter frequencies ranging from 100 Hz to 100 kHz.

Problem #2: Jitter can severely degrade the anti-alias filters in an oversampling converter. This is a little known but easily measurable effect. Most audio converters operate at high oversampling ratios. This allows the use of high-performance digital anti-alias filters in place of the relatively poor performing analog anti-alias filters. In theory, digital anti-alias filters can have extremely sharp cutoff characteristics, and very few negative effects on the in-band audio signal. Digital anti-alias filters are usually designed to achieve at least 100 dB of stop-band attenuation. But, digital filters are designed using the mathematical assumption that the time interval between samples is a constant. Unfortunately, sample clock jitter in an A/D or D/A varies the effective time interval between samples. This variation alters the performance of these carefully designed filters. Small amounts of jitter can severely degrade stop-band performance, and can render these filters useless for preventing aliasing.

The obvious function of a digital anti-alias filter is the removal of audio tones that are too high in frequency to be represented at the selected sample rate. The not-so-obvious function is the removal of high-frequency signals that originate inside the converter box, or even originate inside the converter IC. These high-frequency signals are a result of crosstalk between digital and analog signals, and may have high amplitudes in a poorly designed system. Under ideal (low jitter) conditions, the digital anti-alias filter may remove most of this unwanted noise before it can alias down into lower (audio) frequencies. These crosstalk problems may not become obvious until jitter is present.

Stop-band attenuation can be measured very easily by sweeping a test tone between 24 kHz and at least 200 kHz while monitoring the output of the converter.

Put UltraLock™ converters to the test:

We encourage our customers to perform the above tests on UltraLock2™ converters (or let your ears be the judge). There will be absolutely no change in performance as jitter is added to any digital input on an UltraLock2™ converter. Try the same tests on any converter using conventional single or two-stage PLL circuits. Tests should be performed with varying levels of jitter and with varying jitter frequencies. The results will be very enlightening. Jitter related problems have audible (and measurable) effects on A/D and D/A devices. Practitioners of Digital Audio need to understand these effects.

Is it possible to eliminate all of the effects of jitter in an entire digital audio system?

Interface jitter will accumulate throughout even the most carefully designed digital audio system. Fortunately, interface jitter can only degrade digital audio if it affects the sampling circuit in an analog-to-digital or digital-to-analog converter. Any attempt to cure jitter outside of an A/D or D/A will prove expensive and, at best, will only partially reduce jitter-induced artifacts. Dedicated clock signals (word clock, and super clock, etc.) are often distributed to A/D converters and D/A converters in an attempt to reduce jitter. Again, these are only partial solutions because jitter even accumulates in these clock distribution systems. Furthermore, a poor quality master clock generator can degrade the performance of the entire system (if converter performance is dependent upon reference clock quality). Jitter-free A/D and D/A converters are the only true insurance against the ill effects of jitter. UltraLock2™ converters are jitter-immune under all operating conditions (they will never add audible jitter-induced artifacts to an audio signal).

What UltraLock™ converters cannot do:

UltraLock2™ converters cannot undo damage that has already been done. If an A/D with a jitter problem was used to create a


digital audio signal, then there is nothing that can be done to remove the jitter-induced distortion that happened inside the A/D converter. Jitter-induced sidebands are extremely complex and cannot be removed with any existing audio device. Therefore, it is very important to attack jitter at both ends of the audio chain. The DAC2 is a great start, as it will allow accurate assessment of various A/D converters. It is impossible to audibly evaluate A/D performance without a good D/A. The consistent performance delivered by the DAC2 eliminates one major variable - jitter.

Multi-Mode Asynchronous USB

Audio

Plug it in and Start Listening… Immediately

Benchmark's Advanced USB Audio system supports USB Audio 1.1 and USB Audio 2.0 modes. Both modes are frequency agile. The DAC2 will follow sample rate changes initiated by the computer and/or the media playback software.

In all modes the USB communications are asynchronous. An ultra low jitter conversion clock is generated inside the DAC2. The asynchronous USB interface pulls data from the computer without using computer-generated clocks. The D/A conversion in the DAC2 is completely isolated by the asynchronous USB interface and by the UltraLock2™ jitter-attenuation system.

The DAC2 has a low-jitter master clock which controls the transfer of audio data from the computer to the USB sub-system. The computer asynchronously transfers audio data to a buffer in the DAC2. The contents of the buffer are then asynchronously transferred to the D/A conversion sub-system. This second asynchronous transfer eliminates any traces of jitter that accumulate as the data is transferred between the USB and conversion

subsystems. No traces of jitter-induced distortion are measurable to our measurement limits (better than -140 dBFS). This truly represents the state-of-the art. Enjoy the convenience of computer playback without compromise.

The Asynchronous USB system supports USB Audio 2.0 for high-resolution 192kHz, and DSD playback. No drivers are required for MAC operating systems. An easy-to-install driver adds 192 kHz and DSD capabilities to Windows operating systems.

The asynchronous driverless USB Audio 1.1 mode supports sample rates up to 96 kHz. This USB mode can be selected from the front panel or from the remote control. The driverless USB Audio 1.1 mode allows quick plug-and-play connections to Windows, MAC, iOS, and Linux operating systems without installing drivers. Just plug in the USB, and the DAC2 becomes an available audio device. In many cases, audio will automatically be routed to the newly connected device. If not, it can be selected as the current or default playback device.

The industry-standard USB Audio Mode 2.0 mode is not yet natively supported by the current Windows operating systems. For this reason, a driver is required for Windows operating systems. The driver supports Windows XP, Vista, or 7, 8 and 10. This driver is required for DSD and sample rates above 96 kHz when using Windows.

The USB subsystem is computer powered (through the USB cord) and it remains active when the DAC2 is powered down. This feature prevents interruptions to the computer playback operations and eliminates the need to reconfigure the computer every time the converter is turned on.

The Windows driver is available at:

BenchmarkMedia.com/dac/dac2-drivers

https://benchmarkmedia.com/dac/dac2-drivers


USB Driver Installation

Windows Operating Systems

Note: The DAC2 driver is available for download at: BenchmarkMedia.com/dac/dac2-drivers

Before you install the driver, make sure the USB cable is unplugged.

1. In the DAC2 Driver folder, double click “setup.exe.”

https://benchmarkmedia.com/dac/dac2-drivers


2. A welcome screen will pop-up. Click “Next.”

3. When you see the following screen, turn on the DAC2, plug in the USB cable, and select the

USB input on the DAC2. By default, the DAC2 is shipped in USB Audio 1.0 mode. Do not proceed to the next step until the USB Audio 2.0 mode has been enabled. You can enable the USB Audio 2.0 mode using one of the following two methods:

• METHOD 1 - REMOTE CONTROL: Using your remote control, press and hold USB button for 3 seconds (the 4X light should flash once). If the 2X light flashes instead of the 4X light, repeat this step.

• METHOD 1 - FRONT PANEL: From the front panel, simultaneously press and hold both INPUT buttons for three seconds (the 4X light should flash once). If the 2X light flashes instead of the 4X light, repeat this step.


4. You will now be prompted to select a location to install the driver. It will default to your Program Files folder. If you wish to install it another location, you can change the location. We suggest keeping it in the default location. Click “Install”.

5. When the installation begins you will see the following screen. Please be patient while the driver installs. Installation may require several minutes.


6. When the installation finishes a message at the top will say “Installation Complete.” Click “Next” to continue.

7. Click “Finish.” The Setup will close automatically. This completes the installation process. You can now enjoy music over the USB Audio 2.0 connection at sample rates up to 192 kHz. DSD can also be played in DoP 1.1 format.


Performance Graphs

Graph 1 – FFT Idle Channel Noise

The extraordinary performance of the DAC2 is demonstrated by the FFT plot shown above. There is no sign of any AC hum, there are no idle tones, and there are no spurious tones detected at a measurement limit of -160 dBFS.

The rise at 0 Hz is normal in an FFT analysis and is not an indication of noise. This 32k point FFT analysis uses a Blackman-Harris window with 16x power averaging, and spans a frequency range of DC to 32 kHz.

Audio Precision FFT Idle Channel Noise, 0 dBr = 0 dBFS = 23 dBu

DAC2 - FFT Idle Channel Noise.at27

ColorSweep Trace Line Style Thick Data Axis Comment

1 1 Green Solid 4 Fft.Ch.1 Ampl Left1 2 Red Solid 4 Fft.Ch.2 Ampl Right

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0 32k2k 4k 6k 8k 10k 12k 14k 16k 18k 20k 22k 24k 26k 28k 30kHz


Graph 2 - Low Frequency FFT - AC Line-Related Hum

The DAC2 shows no evidence of AC line-related hum to a measurement limit of -160 dBFS. The cursors are placed at 60 Hz and 180 Hz (frequencies where we would expect to see interference from the 60 Hz AC input. There is absolutely no sign of any AC hum.

Audio Precision FFT Idle Channel Noise - Low Frequency, 0 dBr = 0 dBFS = 23 dBu

DAC2 - FFT Idle Channel Noise - Low Frequency.at27

ColorSweep Trace Line Style Thick Data Axis Comment Cursor1 Cursor2

1 1 Green Solid 4 Fft.Ch.1 Ampl Left *-156.413 dBr *-157.539 dBr 1 2 Red Solid 4 Fft.Ch.2 Ampl Right -159.813 dBr A -158.700 dBr A

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d B r A

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d B r A

25 400 50 75 100 125 150 175 200 225 250 275 300 325 350 37560.1566 180.626

Hz

dx=120.470 Hz dy=-1.126 dB


Graph 3 - FFT 10 kHz

The 10 kHz FFT analysis is an excellent test for detecting sample clock jitter. Jitter will create sidebands (unwanted tones) above and below the 10 kHz test tone. A jitter frequency of 1 kHz would create two sideband tones; a lower sideband at 9 kHz, and an upper sideband at 11 kHz. Similarly, a jitter frequency of 2 kHz would produce sideband tones at 8 kHz and 12 kHz. The above plot shows no evidence of jitter-induced sidebands to a measurement limit of about -140 dBFS.

The -140 dB measurement limit is due to the SNR limitations of the Audio Precision 2700 test set, and not the DAC2. Note the very low harmonic distortion; -114 to -116 dB 2nd harmonic (20 kHz), and -120 to -122 dB 3rd harmonic (30 kHz). Please note that these are almost exactly the same harmonic distortion levels that occur with a 1 kHz tone (see Graph 4 - FFT 1 kHz). This demonstrates that the DAC2 analog stages have the high slew rates required to pass high-amplitude high-frequency signals without an increase in harmonic distortion.


Audio Precision DAC2 - FFT 10 kHz, 0 dBr = 0 dBFS = 23 dBu

DAC2 - FFT 10 kHz.at27



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dBr A

0 32k2k 4k 6k 8k 10k 12k 14k 16k 18k 20k 22k 24k 26k 28k 30k20.0391k 30.0587k

Hz

dx=10.0196 kHz dy=-5.604 dB


Graph 4 - FFT 1 kHz

The 1 kHz FFT analysis demonstrates the low harmonic distortion of the DAC2. Second harmonic distortion (2 kHz) measures about -115 dB, while 3rd harmonic distortion measures -128 to -130 dB.


Audio Precision DAC2 - FFT 1 kHz, 0 dBr = 0 dBFS = 23 dBu

DAC2 - FFT 1 kHz.at27



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0 3.2k200 400 600 800 1k 1.2k 1.4k 1.6k 1.8k 2k 2.2k 2.4k 2.6k 2.8k 3k2.00391k 2.99961k

Hz

dx=.995695 kHz dy=-13.022 dB


Graph 5 - Frequency Response

This plot demonstrates the ruler-flat frequency response of the DAC2. Note that the frequency response measures - 0.01 dB at 10 Hz and -0.02 dB at 40 kHz.

Audio Precision 10/24/12 16:02:03DAC2 - FREQUENCY RESPONSEFs = 96 kHz

DAC2 - Frequency Response.at27


1 1 Green Solid 4 Anlr.Level A Left -0.011 dBr A -0.026 dBr A1 2 Red Solid 4 Anlr.Level B Right *-0.009 dBr *-0.020 dBr

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5k 45k10k 15k 20k 25k 30k 35k 40k10.0021 40.4214k

Hz

dx=40.4114 kHz dy=-0.011 dB


Graph 6 - Differential Phase

This plot demonstrates the inter-channel phase accuracy of the DAC2. From this plot, the inter-channel phase accuracy is calculated to be +/- 0.17 degrees at 20 kHz, and +/- 0.34 degrees at 40 kHz.

The phase accuracy of the DAC2 is almost the same as the phase accuracy of the Audio Precision 2700 test set. For this reason, the phase error in the AP must be subtracted from the measurement. The green trace assigns the left channel to channel 1 of the AP, and the right channel to channel 2 of the AP. The red trace reverses the inputs. The two traces must be averaged to remove the phase errors of the AP test set.

DAC2 converters are phase-accurate between boxes. Three DAC2 converters can be used as a group to form a phase-accurate 5.1 surround system. Four DAC2 converters can be combined to form a 7.1 system. The phase accuracy between any two channels will match the phase accuracy shown above.

Audio Precision DAC2 - Differential PhaseFs = 96 kHz

DAC2 - Differential Phase.at27


1 1 Green Solid 4 Anlr.Phase Left -0.09 deg -0.21 deg2 1 Red Solid 4 Anlr.Phase Left *+0.24 deg *+0.47 deg

-1

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deg

2.5k 45k5k 7.5k 10k 12.5k 15k 17.5k 20k 22.5k 25k 27.5k 30k 32.5k 35k 37.5k 40k 42.5k20.2555k 40.0511k

Hz

dx=19.7956 kHz dy=+0.23 deg


Graph 7 - Balanced THD+N vs. Amplitude

This plot demonstrates the very low harmonic distortion produced by the DAC2 at signal levels ranging from -14 dBFS to 0 dBFS. All variations below -4 dBFS are due to the measurement limits of the AP 2700 system. The peaks at -13 dBFS are due to an AP 2700 gain range change. In almost all listening environments, THD will be below the threshold of hearing. The DAC2 is virtually uncolored by any trace of harmonic distortion.

The DAC2 includes differential amplifiers that remove common-mode distortion components. This is important, because common-mode distortion is not detected when measuring with the precisely-balanced inputs on the AP 2700 test set. The THD+N measurements on the unbalanced outputs confirm the effectiveness of the differential amplifiers. Similar results are obtained by measuring either side of the balanced outputs relative to ground.

Audio Precision DAC2 - THD+N vs AMPLITUDE AT 1 KHZ (w/20 kHz LPF unweighted)Balanced Outputs, Relative to 0 dBFS, 0 dBFS = +23 dBu

DAC2 - Balanced THD+N vs AMPLITUDE.at27


1 1 Green Solid 4 Anlr.THD+N Ampl Left1 2 Red Solid 4 Anlr.THD+N Ampl Left

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-14 -0-13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1dBFS


Graph 8 - Unbalanced THD+N versus Amplitude

This plot shows the THD+N performance of the unbalanced outputs. Note that the THD+N performance of the unbalanced outputs approaches that of the balanced outputs. The DAC2 includes differential amplifiers that remove common-mode THD from the balanced outputs of the SABRE converters. These differential amplifiers give the unbalanced outputs the ability to approach the performance of the balanced outputs. Please note that the differential amplifiers also eliminate common-mode distortion on the balanced outputs.

Audio Precision DAC2 - THD+N vs AMPLITUDE AT 1 KHZ (w/20 kHz LPF unweighted)Unbalanced Outputs, Relative to 0 dBFS, 0 dBFS = +7.2 dBu

DAC2 - Unbalanced THD+N_VS_AMPLITUDE.at27



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Graph 9 - Headphone Amplifier – THD+N versus Amplitude (DAC2 HGC model only)

This plot shows the THD+N performance of the headphone outputs under load. Note that the THD+N performance of the headphone outputs approaches that of the balanced outputs. The DAC2 includes Benchmark's HPA2™ headphone amplifier. The HPA2™ has a near 0-Ohm output impedance which provides outstanding control and damping of the headphone drivers. The HPA2™ has the voltage and current drive necessary to drive a wide variety of headphones.

Audio Precision DAC2 - THD+N vs AMPLITUDE AT 1 KHZ (w/20 kHz LPF unweighted)Headphone Outputs, Relative to 0 dBFS, 0 dBFS = +7.2 dBu

DAC2 - HEADPHONE - THD+N_VS_AMPLITUDE.at27



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-14 -0-13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1dBFS


Graph 10 - THD+N vs. Frequency 80 kHz

The analog output stages on the DAC2 have high slew rates and are capable of maintaining low THD levels at high frequencies even when driven to 0 dBFS. Note that there is almost no rise in THD+N with frequency, even when operating at maximum output levels.

Audio Precision DAC2 - THD+N VS FREQ AT 0 dBFS (w/80 kHz LPF unweighted)

Balanced Outputs

DAC2 - THD+N vs FREQUENCY 80kHZ.at27

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20 20k 50 100 200 500 1k 2k 5k 10k Hz


Graph 11 - Even And Odd THD vs. Frequency

This plot demonstrates that the harmonic distortion of the DAC2 is lower than the THD+N numbers would suggest. This plot shows THD not THD+N. Even and odd harmonic distortions are plotted separately. Note that odd harmonics are lower than the more "musical" even harmonics. Both sets of harmonics are very low in amplitude (-112 dB to -120 dB), and should be entirely inaudible.

Audio Precision DAC2 - THD VS FREQ AT 0 dBFS Balanced Outputs

DAC2 - EVEN AND ODD THD vs FREQUENCY.at27


1 1 Green Solid 4 Distortion.Ch.1 Harm Sum1 Ratio Left *-115.210 dB *-112.066 dB1 2 Red Solid 4 Distortion.Ch.1 Harm Sum2 Ratio Right -115.165 dB -120.544 dB

GREEN = EVEN HARMONIC DISTORTION (2,4,6,8,10,12,14) RED = ODD HARMONIC DISTORTION (3,5,7,9,11,13,15)

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-112.066

d B

20 10k 50 100 200 500 1k 2k 5k1.00318k 10k

Hz

dx=8.99682 kHz dy=+3.144 dB


Graph 12 - THD vs. Frequency - All Outputs

This plot demonstrates that all of the analog outputs on the DAC2 have very similar performance over the entire audio band. The unbalanced outputs, and the headphone outputs, closely match the performance of the balanced outputs. Like Graph 11 - Even And Odd THD vs. Frequency, this plot shows THD (not THD+N).

Audio Precision DAC2 - THD VS FREQ AT 0 dBFS - ALL OUTPUTS

DAC2 - THD vs FREQUENCY.at27

ColorSweep Trace Line Style Thick Data Axis Comment Source 2 Cursor1

1 2 Blue Solid 4 Distortion.Ch.1 Harm Sum1 Ratio Left : 1.00000 =Swr.Ch. A+B Input -112.557 dB1 3 Cyan Solid 4 Distortion.Ch.2 Harm Sum1 Ratio Right : 1.00000 =Swr.Ch. A+B Input -112.453 dB2 2 Red Solid 4 Distortion.Ch.1 Harm Sum1 Ratio Left : 3.00000 =Swr.Ch. A+B Input -113.919 dB2 3 Magenta Solid 4 Distortion.Ch.2 Harm Sum1 Ratio Right : 3.00000 =Swr.Ch. A+B Input -113.349 dB3 2 Green Solid 4 Distortion.Ch.1 Harm Sum1 Ratio Left : 5.00000 =Swr.Ch. A+B Input -117.017 dB3 3 Yellow Solid 4 Distortion.Ch.2 Harm Sum1 Ratio Right : 5.00000 =Swr.Ch. A+B Input *-114.827 dB

1=Balanced L 2=Balanced R 3=Unbalanced L 4=Unbalanced R 5=Headphone L 6=Headphone R

-130

-90

-125

-120

-115

-110

-105

-100

-95

-114.827

-106.739 d B

-130

-90

-125

-120

-115

-110

-105

-100

-95

d B

20 10k 50 100 200 500 1k 2k 5k1.00318k 10k

Hz

dx=8.99682 kHz dy=+8.088 dB


Graph 13 - THD+N versus Sample Rate

The THD+N performance of the DAC2 is identical at all Sample Rates.

Benchmark Media Systems, Inc. DAC2 - THD+N vs Sample Rate, 1 kHz at 0 dBFS (w/20 kHz LPF unweighted)Balanced Outputs

DAC2 - THD+N vs Sample Rate.at27


1 1 Green Solid 4 Anlr.THD+N Ratio Left1 2 Red Solid 4 Anlr.THD+N Ratio Left

-120

-90

-117.5

-115

-112.5

-110

-107.5

-105

-102.5

-100

-97.5

-95

-92.5

dB

40k 200k60k 80k 100k 120k 140k 160k 180kHz


Graph 14 - Jitter Tolerance

The Audio Engineering Society (AES) has created a jitter tolerance template for testing digital audio devices. The red curve shows the AES jitter tolerance template. Induced jitter approaches 5 UI at 200 Hz, and is reduced to 0.125 UI above 8 kHz. The green trace shows the THD+N of the DAC2 while being driven with the jitter shown on the red curve. Over the entire range of the AES jitter tolerance test, the THD+N performance of the DAC2 is unchanged. The DAC2 easily passes the AES jitter tolerance test without any THD+N performance degradation.

Audio Precision DAC2 - INTERFACE JITTER TOLERANCE - Distortion vs Jitter3.456 kHz Test Tone at 0 dBFS, THD+N 22 to 22 kHz BW

DAC2 - JITTER TOLERANCE.at27


1 1 Green Solid 4 Anlr.THD+N Ratio Left1 2 Red Solid 4 Dio.Interface Jitter Right

DAC2 THD+N (22-22kHz) (Green Trace) vs. Interface Jitter (Red Trace)Digital Input = 3.456 kHz Tone at 0 dBFS, Fs = 48 kHz

10m

20

20m

50m

100m

200m

500m

1

2

5

10

UI

-110

+0

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

dB

100 90k200 500 1k 2k 5k 10k 20k 50kHz


Graph 15 - Jitter Tolerance FFT

This figure shows a series of FFTs that were acquired while running the AES jitter tolerance test. Note that none of the 31 FFTs show any signs of jitter-induced sidebands. Note that the plots are identical to the plots shown in Graph 4 - FFT 1 kHz. The DAC2 shows no change in performance when the AES jitter tolerance test is applied to the digital inputs. No jitter-induced sidebands are visible to a measurement limit that exceeds -140 dBFS.

Audio Precision DAC2 - INTERFACE JITTER TOLERANCE FFT 10 kHz Test Tone at 0 dBFS, AES Jitter Tolerance Sweep

-140

+0

-120

-100

-80

-60

-40

-20

d B r A

0 32k 2k 4k 6k 8k 10k 12k 14k 16k 18k 20k 22k 24k 26k 28k 30k Hz

DAC2 - JITTER TOLERANCE FFT.at27

ColorSweep Trace Line Style Thick Data Axis Comment Source 2

1 2 Green Solid 4 Fft.Ch.1 Ampl Left : 100.000 Hz=Dio.Jitter Freq2 2 Red Solid 4 Fft.Ch.1 Ampl Left : 125.893 Hz=Dio.Jitter Freq3 2 Red Solid 1 Fft.Ch.1 Ampl Left : 158.489 Hz=Dio.Jitter Freq4 2 Magenta Solid 1 Fft.Ch.1 Ampl Left : 199.526 Hz=Dio.Jitter Freq5 2 Blue Solid 1 Fft.Ch.1 Ampl Left : 251.189 Hz=Dio.Jitter Freq6 2 Cyan Solid 1 Fft.Ch.1 Ampl Left : 316.228 Hz=Dio.Jitter Freq7 2 Green Solid 1 Fft.Ch.1 Ampl Left : 398.107 Hz=Dio.Jitter Freq8 2 Yellow Solid 1 Fft.Ch.1 Ampl Left : 501.187 Hz=Dio.Jitter Freq9 2 Red Solid 1 Fft.Ch.1 Ampl Left : 630.957 Hz=Dio.Jitter Freq10 2 Magenta Solid 1 Fft.Ch.1 Ampl Left : 794.328 Hz=Dio.Jitter Freq11 2 Blue Solid 1 Fft.Ch.1 Ampl Left : 1.00000 kHz=Dio.Jitter Freq12 2 Cyan Solid 1 Fft.Ch.1 Ampl Left : 1.25893 kHz=Dio.Jitter Freq13 2 Green Solid 1 Fft.Ch.1 Ampl Left : 1.58489 kHz=Dio.Jitter Freq14 2 Yellow Solid 1 Fft.Ch.1 Ampl Left : 1.99526 kHz=Dio.Jitter Freq15 2 Red Solid 1 Fft.Ch.1 Ampl Left : 2.51189 kHz=Dio.Jitter Freq16 2 Magenta Solid 1 Fft.Ch.1 Ampl Left : 3.16228 kHz=Dio.Jitter Freq17 2 Blue Solid 1 Fft.Ch.1 Ampl Left : 3.98107 kHz=Dio.Jitter Freq18 2 Cyan Solid 1 Fft.Ch.1 Ampl Left : 5.01187 kHz=Dio.Jitter Freq19 2 Green Solid 1 Fft.Ch.1 Ampl Left : 6.30957 kHz=Dio.Jitter Freq20 2 Yellow Solid 1 Fft.Ch.1 Ampl Left : 7.94328 kHz=Dio.Jitter Freq21 2 Red Solid 1 Fft.Ch.1 Ampl Left : 10.0000 kHz=Dio.Jitter Freq22 2 Magenta Solid 1 Fft.Ch.1 Ampl Left : 12.5893 kHz=Dio.Jitter Freq23 2 Blue Solid 1 Fft.Ch.1 Ampl Left : 15.8489 kHz=Dio.Jitter Freq24 2 Cyan Solid 1 Fft.Ch.1 Ampl Left : 19.9526 kHz=Dio.Jitter Freq25 2 Green Solid 1 Fft.Ch.1 Ampl Left : 25.1189 kHz=Dio.Jitter Freq26 2 Yellow Solid 1 Fft.Ch.1 Ampl Left : 31.6228 kHz=Dio.Jitter Freq27 2 Red Solid 1 Fft.Ch.1 Ampl Left : 39.8107 kHz=Dio.Jitter Freq28 2 Magenta Solid 1 Fft.Ch.1 Ampl Left : 50.1187 kHz=Dio.Jitter Freq29 2 Blue Solid 1 Fft.Ch.1 Ampl Left : 63.0957 kHz=Dio.Jitter Freq30 2 Cyan Solid 1 Fft.Ch.1 Ampl Left : 79.4328 kHz=Dio.Jitter Freq31 2 Green Solid 4 Fft.Ch.1 Ampl Left : 100.000 kHz=Dio.Jitter Freq


Graph 16 - IMD 11k 12K

This plot demonstrates that the DAC2 has very low IMD distortion. The 1 kHz difference frequency measures -122 dB, and the 10 kHz and 13 kHz products measure about -128 dB. IMD distortion should be well below audible levels.

Audio Precision 11/06/12 08:15:12 DAC2 - 11K 12K IMD

DAC2 - IMD 11K 12K.at27

-160

+0

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

d B r A

-160

+0

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

-122.154-128.885

d B r A

0 20k 2k 4k 6k 8k 10k 12k 14k 16k 18k1.01761k 10.0196k

Hz

dx=9.00196 kHz dy=-6.731 dB


Specifications

Audio Performance Fs = 44.1 to 96 kHz, 20 to 20 kHz BW, 1 kHz test tone, 0 dBFS = +24 dBu (unless noted) SNR – A-Weighted, 0 dBFS = +20 to +29 dBu 126 dB SNR – Unweighted, 0 dBFS = +20 to +29 dBu 123 dB THD+N, 1 kHz at 0 dBFS -109 dBFS, -109 dB, 0.00035% THD+N, 1 kHz at -1 dBFS -110 dBFS, -109 dB, 0.00035% THD+N, 1 kHz at –3 dBFS -113 dBFS, -109 dB, 0.00035% THD+N, 20 to 20 kHz test tone at –3 dBFS -112 dBFS, -108 dB, 0.00040% Frequency Response at Fs=96 kHz +0 dB, -0.04 dB (20 to 20 kHz)

-0.04 dB at 10 Hz -0.04 dB at 20 kHz -0.04 dB at 40 kHz -0.7 dB at 45 kHz

Frequency Response at Fs=48 kHz +0 dB, -0.04 dB (20 to 20 kHz) -0.04 dB at 10 Hz -0.04 dB at 20 kHz

Crosstalk -116 dB at 20 kHz -130 dB at 1 kHz -137 dB at 20 Hz

Maximum Amplitude of Jitter Induced Sidebands (10 kHz 0 dBFS test tone, 12.75 UI sinusoidal jitter at 1 kHz)

< -144 dB

Maximum Amplitude of Spurious Tones with 0 dBFS test signal

< -138 dB

Maximum Amplitude of Idle Tones < -147 dB Maximum Amplitude of AC line related Hum & Noise < -140 dB Inter-channel Differential Phase (Stereo Pair – any sample rate)

+/- 0.25 degrees at 20 kHz

Inter-channel Differential Phase (Between DAC2 Units Fs<110 kHz) Any sample rate.

+/- 0.25 degrees at 20 kHz

Maximum Lock Time after Fs change 400 ms Soft Mute Ramp Up/Down Time 50 ms Mute on Receive Error Yes Mute on Lock Error Yes Mute on Idle Channel No 50/15 us De-Emphasis Enable Automatic in Consumer Mode De-Emphasis Method Digital IIR De-Emphasis Supported at Fs = 32, 44.1, 48 kHz


Group Delay (Latency) Delay – Digital Input to Analog Output (function of sample rate)

1.36 ms at 44.1 kHz

1.27 ms at 48 kHz

0.90 ms at 88.2 kHz

0.82 ms at 96 kHz

0.51 ms at 176.4 kHz

0.47 ms at 192 kHz

Digital Audio Inputs Number of Digital Inputs (switch selected) 5 (1 USB, 2 Optical, 2 Coaxial) Number of Channels 2 Input Sample Frequency Range 28 to 210 kHz (Coaxial Inputs)

28 to 96 kHz (Optical Inputs)

44.1, 48, 88.2, 96, 176.4, 192 kHz (USB Input)

Maximum Input Word Length 24 bits Digital Input Impedance 75 Ohms (Coaxial Inputs) DC Blocking Capacitors on Digital Inputs Yes (Coaxial Inputs) Transient and Over-Voltage Protection on Digital Inputs Yes (Coaxial Inputs) Minimum Digital Input Level 250 mVpp (Coaxial Inputs)

Jitter Tolerance (With no Measurable Change in Performance)

>12.75 UI sine, 100 Hz to 3 kHz

>1.5 UI sine at 20 kHz




>0.25 UI sine above 160 kHz Jitter Attenuation Method Benchmark UltraLock2™ - all inputs


Balanced Analog Outputs Number of Balanced Analog Outputs 2 Output Connector Gold-Pin Neutrik™ male XLR Output Impedance 60 Ohms (Attenuator off)

425 Ohms (Attenuator = 10 dB)

135 Ohms (Attenuator = 20 dB) Analog Output Clip Point +29 dBu Factory Set Bypass Level (at 0 dBFS) +24 dBu (Attenuator = 0 dB) Output Level Range (at 0 dBFS) In ‘Variable’ Mode Off to +24 dBu (Attenuator off)

Off to +14 dBu (Attenuator = 10 dB)

Off to +4 dBu (Attenuator = 20 dB) Output Level Variation with Sample Rate (44.1 kHz vs. 96 kHz)

< +/- 0.006 dB

Unbalanced Analog Outputs Number of Unbalanced Analog Outputs 4 Output Connector RCA Output Impedance 30 Ohms Analog Output Clip Point +13.5 dBu (3.7 Vrms) Factory Set Home Theater Bypass Output Level (at 0 dBFS)

+8.2 dBu (2 Vrms)

Output Level Range (at 0 dBFS) Off to +8.2 dBu (2 Vrms) Output Level Variation with Sample Rate (44.1 kHz vs. 96 kHz)

< +/- 0.006 dB

HPA2TM Headphone Outputs Number of Headphone Outputs 2 Output Connectors ¼” TRS with switch on left-hand jack Output Impedance < 0.11 Ohms Output Level Control Stereo Control on Front Panel Output Level Range (at 0 dBFS) into 60-Ohm Load Off to +18 dBu Maximum Output Current 250 mA Overload Protection (independent per channel) Current limited at 300 mA, Thermal Bandwidth > 500 kHz THD+N -106 dB, 0.0005% into 30 Ohms at

+18 dBu (1.26W into 30 Ohms)


Unbalanced Analog Inputs Number of Unbalanced Analog Inputs 4 Input Connector RCA Input Impedance 20 K Ohms Analog Input Clip Point +18.5 dBu (6.5 Vrms) Input Sensitivity +8.2 dBu (2 Vrms)

AC Power Requirements Nominal Input Operating Voltage Range (VAC RMS) 100 – 240V Frequency 50-60 Hz Power < 0.5 Watts Idle

12 Watts Typical Program 15 Watts Maximum

Fuses 5 x 20 mm (2 required) 0.5 A 250 V Slo-Blo® Type

Min/Max Operating range (VAC RMS) 90 – 260 47 – 63Hz

Dimensions Form Factor ½ Rack Wide, 1 RU High Depth behind front panel 8.5” (216 mm) Overall depth including connectors but without power cord

9.33” (237 mm)

Width 9.5” (249 mm) Height 1.725” (44.5 mm)

Weight DAC2 only 3 lb. DAC2 with accessories and manual 4 lb. Shipping weight 7 lb.

Status Display Indicators - Type and Location 16 LED’s on Front Panel Selection/Status Indication 1 – Dim/Mute

1 - Polarity 7 – Input 1 – Bypass/Calibrated Output 2 – Word length 4 – Sample Rate


Regulatory Compliance

FCC and RoHS Compliance Statements

RoHS Compliant Information

This statement clarifies Benchmark Media Systems, Inc. product compliance with the EU’s (European Union) directive 2002/95/EC, or, RoHS (Restrictions of Hazardous Substances).

As of July 01, 2006, All Benchmark Media Systems, Inc. products placed on the European Union market are compliant (containing quantity limit weight less than or equal to 0.1% (1000 ppm) of any homogeneous Lead (Pb), Mercury (Hg), Hexavalent Chromium (Cr VI), and flame retardant Polybrominated Biphenyls (PBB) or Polybrominated Diphenyl Ethers (PBDE)).

FCC Notice (U.S. Only)

NOTICE: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:

• Reorient or relocate receiving antenna. • Increase the separation between the equipment and receiver. • Connect the equipment into an outlet on a circuit different from that to which the receiver is

connected. • Consult the dealer or an experienced radio/TV technician for help.

This device complies with Part 15 of the FCC rules. Operation is subject to the following two conditions:

1. This device may not cause harmful interference. 2. This device must accept any interference received including interference that may cause

undesired operation.

Instructions to Users: This equipment complies with the requirements of FCC (Federal Communication Commission) equipment provided that following conditions are met:

• RCA Digital Connections: Shielded 75-Ohm coaxial cable must be used.

NOTICE: Changes or modifications not expressly approved by the party responsible for compliance could void the user's authority to operate the equipment.


CE Certificates of Conformity


Warranty Information

Benchmark 1-Year Warranty

The Benchmark 1-Year Warranty

Benchmark Media Systems, Inc. warrants its products to be free from defects in material and workmanship under normal use and service for a period of one year from the date of delivery.

This warranty extends only to the original purchaser. This warranty does not apply to fuses, lamps, batteries, or any products or parts that have been subjected to misuse, neglect, accident, modification, or abnormal operating conditions.

In the event of failure of a product under this warranty, Benchmark Media Systems, Inc. will repair, at no charge, the product returned to its factory. Benchmark Media Systems, Inc. may, at its option, replace the product in lieu of repair. If the failure has been caused by misuse, neglect, accident, or, abnormal operating conditions, repairs will be billed at the normal shop rate. In such cases, an estimate will be submitted before work is started, if requested by the customer.

Attempts to deliberately deface, mutilate, or remove the product's label will render this warranty void. Benchmark will not honor warranties for any products disingenuously purchased on the US or Canadian markets for export.

The foregoing warranty is in lieu of all other warranties, expressed or implied, including but not limited to any implied warranty of merchantability, fitness or adequacy for any particular purpose or use. Benchmark Media Systems, Inc. shall not be liable for any special, incidental, or consequential damages, and reserves the right to change this information without notice. This limited warranty gives the consumer-owner specific legal rights, and there may also be other rights that vary from state to state.


Benchmark Extended Warranty Options

The Benchmark Extended 5-Year Warranty *

Benchmark Media Systems, Inc. optionally extends the standard 1-year warranty to a period of five years from the date of delivery.

*For the extended warranty to become effective, the original purchaser must register the product at the time of purchase either by way of the enclosed registration card or through the product registration section of the Benchmark Media Systems, Inc. website. This optional warranty applies only to products purchased within the US and Canada and is extended only to the original purchaser.

Attempts to deliberately deface, mutilate, or remove the product's label will render this warranty void. Benchmark will not honor warranties for any products disingenuously purchased on the US or Canadian markets for export. The terms of the extended warranty are subject to change without notice. For products purchased outside the US and Canada, please refer to the Extended Two 2-Year International Warranty.

The Benchmark Extended 2-Year International Warranty **

Benchmark Media Systems, Inc. optionally extends the standard 1-year warranty to a period of two years from the date of delivery.

**For the extended warranty to become effective, the original purchaser must register the product at the time of purchase either by way of the enclosed registration card or through the product registration section of the Benchmark Media Systems, Inc. website. This optional warranty applies only to products purchased outside the US and Canada and is extended only to the original purchaser.

Attempts to deliberately deface, mutilate, or remove the product's label will render this warranty void. Benchmark will not honor warranties for any products disingenuously purchased on the US or Canadian markets for export. The terms of the extended warranty are subject to change without notice. For products purchased in within the US and Canada, please refer to the Extended Five 5-Year Warranty.

Notes on Warranty Repairs

An RMA (return merchandise authorization) number, issued by our Customer Service Department, is required when sending products for repair.

They must be shipped to Benchmark Media Systems prepaid and preferably in their original shipping carton with the RMA number clearly visible on the exterior of the packaging. A letter should be included giving full details of the difficulty.


Copyright © 2007, 2008, 2009, 2012, 2013, 2014, 2015, 2016 Benchmark Media Systems, Inc.

All rights reserved.

Benchmark Media Systems, Inc. Benchmark Media Systems, Inc. 203 East Hampton Place, STE 2

Syracuse, NY 13206-1633 USA

PHONE: +1-315-437-6300 FAX: +1-315-437-8119

benchmarkmedia.com

http://benchmarkmedia.com/

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